Xfinity - using your own modem/router or theirs

[sh0rty]

There are many similar posts to this and I have read most, but wanted to know if anyone starting their xfinity service with the ISP provided router and then switched back to their own and the results. I have always used my own modem, and router through Comcast, spectrum and abroad. In Texas I was using a CM1200 on Spectrum and was getting consistent crashes and chalk it up to the ISP not updating the firmware and me not having the ability to do it. I bought an Arris S33 and all my problems went away. Now, I have moved to Florida and on xfinity. During setup they said I can use my own modem, but it would not be unlimited unless I paid an additional fee, or I could use their modem/router for a fee but the data would be unlimited. I chose using theirs in passthough mode to my router to see what it would be. I am on the 1200 Mbps plan and notice that the wifi (the xfinity is disabled) via my router/mesh is like 500 Mbps or so.

I just reconfigured my office in order to hardwire main rig and now getting in the 700-800 mbps range...upload has been consistent around 30-40. This has been since October since I started, but I travel for work so I am not always watching. Now that I have my office setup and plan on going back to see why the speeds are not higher. I plan on calling them this next week, but curios to know if I just go back to my Arris S33 and give them back their modem if the speeds would then fall in line with what I am paying. Has anyone gone between xfiinity devices and then to their own? If yes....what say you?

 

[BlueLineSwinger]

I haven't done any experimentation with the Comcast-provided units, but I do get a consistent >950 Mb/s (i.e., the expected for gigabit service) using my own Netgear CM1150V.

Does the Comcast modem offer up any diagnostics for the upstream connection, so you can get details on signal/noise, dropped/errors, etc.?

I'd also look at your cabling. Make sure all the lines are proper RG-6 (preferably quad-shielded), there are no unnecessary splits and/or open connections, etc., all splitters support the full frequency range, and so on.

edit: Mb, not MB (d'oh)

 

[sh0rty]

I haven't done any experimentation with the Comcast-provided units, but I do get a consistent >950 MB/s (i.e., the expected for gigabit service) using my own Netgear CM1150V.

Does the Comcast modem offer up any diagnostics for the upstream connection, so you can get details on signal/noise, dropped/errors, etc.?

I'd also look at your cabling. Make sure all the lines are proper RG-6 (preferably quad-shielded), there are no unnecessary splits and/or open connections, etc., all splitters support the full frequency range, and so on.

Once I changed the modem to passthrough, I really only see a message that says just that. I can run speeds tests as I am sure you know via wifi devices, hard wired devices and using multiple sites to try and all are consistent and have yet to get ANYTHING over 900. Since xfinity has a plan for 800 mbps then I am thinking that there is something...maybe even something you mentioned. At the time of set up and the last few months of it running I did not really invest any time into it, but now that I have my server and NAS running I want to get to the root. I think the things you mentioned are worthy of more investigating, but upon installation the tech said there was noise on the line. I think calling them is the first step to see what they can find, but I am ready to put my equipment back in mix as well. Was just seeing if anyone had similar results.

 

[SamirD]

I actually did exactly what you mentioned--started with their modem, got my own and went back and forth before getting rid of theirs.

When their modem was in 'modem only mode' it was identical to mine in performance. Now, because both are truly 'modems', one may have less/more noise than another and this can affect performance.

 

[sh0rty]

I actually did exactly what you mentioned--started with their modem, got my own and went back and forth before getting rid of theirs.

When their modem was in 'modem only mode' it was identical to mine in performance. Now, because both are truly 'modems', one may have less/more noise than another and this can affect performance.

I am thinking that the Arris S33 will outperform theirs, but that is my opinion. You state that you "went back and forth before getting rid of theirs"...meaning you are using yours right now? Can you share model number/manufacturer? I am still going to call them, but I feel better with my own stuff....we will see what they say.

 

[Rattle]

I'm using my own, I have 800mbps service. Wired on my PC I've seen up to 950. Wifi 6 5ghz on my S20 5G I've seen up to 750.

Comcast/Xfinity still sucks

 

[sh0rty]

I'm using my own, I have 800mbps service. Wired on my PC I've seen up to 950. Wifi 6 5ghz on my S20 5G I've seen up to 750.

Comcast/Xfinity still sucks

Yeah...I think I am putting my equipment in the mix. Thanks for reply!

 

[SamirD]

I am thinking that the Arris S33 will outperform theirs, but that is my opinion. You state that you "went back and forth before getting rid of theirs"...meaning you are using yours right now? Can you share model number/manufacturer? I am still going to call them, but I feel better with my own stuff....we will see what they say.

I've been with them since 2018 in two different cities and a couple of different plans. I started out with a 150/25? plan where I was on their modem. I needed to have a public IP on my equipment without any filtering so I had to finally get my own modem--sb6190. And then swapped back and forth a few times to see if there were any speed or other issues and if there was a way to get their equipment to behave. There wasn't so I dropped their modem and added an Archer c5 as an access point.

Since that time, I changed the plan to 300/25 and then when we moved the plan changed to 400/10 and then 600/10, 600/15, and now 800/15--all on the same sb6190 modem.

And as a side note on the sb6190 since people talk about the 'puma' scare, I've had zero issues as I use one on my end and one on the other end of a 24x7 nailed up ipsec tunnel that runs rdp sessions through it (latency sensitive). If there were any unmitigated issues with these modems, I would be feeling them and I don't.

 

[SamirD]

I'm using my own, I have 800mbps service. Wired on my PC I've seen up to 950. Wifi 6 5ghz on my S20 5G I've seen up to 750.

Comcast/Xfinity still sucks

You have a combo unit or just a straight modem and separate router?

I have 5 isp accounts at 4 different sites and Comcast has been one of the better ones. Of all my accounts, wow is the worst one--their intermittent packet loss has been a pain.

 

[sh0rty]

You have a combo unit or just a straight modem and separate router?

I have 5 isp accounts at 4 different sites and Comcast has been one of the better ones. Of all my accounts, wow is the worst one--their intermittent packet loss has been a pain.

I am running the xfinity modem, a R9000 router and a DECO M9 plus mesh. As mentioned, I would have the Arris as the modem and feel like it was a solid setup. The xfinity modem is "x" factor. I have to follow up with xfinity to see if there is indeed noise or whatever.

 

[Rattle]

You have a combo unit or just a straight modem and separate router?

I have 5 isp accounts at 4 different sites and Comcast has been one of the better ones. Of all my accounts, wow is the worst one--their intermittent packet loss has been a pain.

It's a nighthawk combo unit.

 

[SamirD]

I am running the xfinity modem, a R9000 router and a DECO M9 plus mesh. As mentioned, I would have the Arris as the modem and feel like it was a solid setup. The xfinity modem is "x" factor. I have to follow up with xfinity to see if there is indeed noise or whatever.

Generally, I've found zero difference between isp issues and on their equipment versus your own. 99% of the time there's an issue, it's on the isp's side.

 

[SamirD]

It's a nighthawk combo unit.

Got it. Makes sense.

 

[Grentz]

I usually like to use my own equipment, but with xFi have the White Advanced Gateway (XB7). It has been flawless in bridge mode with my Unifi Security Gateway (Router).

 

[SamirD]

I usually like to use my own equipment, but with xFi have the White Advanced Gateway (XB7). It has been flawless in bridge mode with my Unifi Security Gateway (Router).

Doesn't surprise me as these are pretty much made by arris so they're the same modem in modem mode.

 

[sh0rty]

I usually like to use my own equipment, but with xFi have the White Advanced Gateway (XB7). It has been flawless in bridge mode with my Unifi Security Gateway (Router).

My xfinity modem shows as a TECHNICOLOR CGM4331COM. Is this an XB7? I mean its white. I can get like 800 from their speed test via hard wire, but anything wifi is like 500 via netgear mesh...nothing near the 1200 my contract has. mostly get 500-600 wired as well...anything over 800 is rare. I have mine in bridge and

 

[SamirD]

Someone's cell phone battery died mid-sentence. They are probably talking for the next 10 minutes like I do before I realize it and call them back.

 

[vegeta535]

When I had Comcast like 6 years ago I didn't have any issues using my own modem. Other then the fact they were charging me for a modem for months before I noticed and wouldn't refund me. I currently have FiOS using one of their old modems I got off eBay for $40. I am even getting 2x the speed I am paying for. FiOS offers a free modem and extender with their gigabit service.

 

[sh0rty]

When I had Comcast like 6 years ago I didn't have any issues using my own modem. Other then the fact they were charging me for a modem for months before I noticed and wouldn't refund me. I currently have FiOS using one of their old modems I got off eBay for $40. I am even getting 2x the speed I am paying for. FiOS offers a free modem and extender with their gigabit service.

Good to know, but this is not available in my area.

 

[Grentz]

My xfinity modem shows as a TECHNICOLOR CGM4331COM. Is this an XB7? I mean its white. I can get like 800 from their speed test via hard wire, but anything wifi is like 500 via netgear mesh...nothing near the 1200 my contract has. mostly get 500-600 wired as well...anything over 800 is rare. I have mine in bridge and

I believe that is the XB7
https://www.xfinity.com/support/articles/broadband-gateways-userguides

So to be clear, you are bumping up to real world rate limits on wifi and 1GB hardwire. Hardwire 1gb in a perfect world is 940mbps.

I always find this funny, because those speeds you are getting are plenty sufficient for any consumer user.

 

[SamirD]

I always find this funny, because those speeds you are getting are plenty sufficient for any consumer user.

It's not a matter of what is sufficient though--it's a matter of what one is paying for versus what one is getting. Just because I can get by with 50Mbs doesn't mean I should be happy with getting that from a 500Mbs plan.

 

[sh0rty]

I always find this funny, because those speeds you are getting are plenty sufficient for any consumer user.

I cannot argue with your statement, but honestly you have no idea what my needs are from this post. However I agree that these speeds are not needed by most and rationally, maybe not even for myself. For reference, I host a server on my home network that I feel warranted this level of service. As SamirD mentioned, this disucussion is about not getting what I am paying for. I mean if I lower what I am paying for, would I get what I am getting now or even less. I am merely trying to figure out if the service gap is associated with the xfinity equipment provided.

 

[AgrFan]

What are the speeds connected directly to each modem? Maximum Data Throughput for both modems is 2.5 Gbps.

Arris S33
Technicolor CGM4331COM

If you get 1200 Mbps (or something close) when connected directly to the modem then the bottleneck is your router.
If you don't get full speed directly connected to the modems, call Xfinity Tech Support and have them look at your signal levels.

I would have Xfinity verify both modems are being sent the proper config file for 1200 Mbps service too.

I have the Performance Pro plan (300 Mbps) and rent a Cisco DPC3941T (XB3) gateway. I get 340 Mbps without breaking a sweat.

I would recommend using the Arris S33 instead of the XB7 gateway since it sounds like you already have a router. No sense paying the $14 modem rental charge.

 

[sh0rty]

What are the speeds connected directly to each modem? Maximum Data Throughput for both modems is 2.5 Gbps.

Arris S33
Technicolor CGM4331COM

If you get 1200 Mbps (or something close) when connected directly to the modem then the bottleneck is your mesh router.
If you don't get full speed directly connected to the modems, call Xfinity Tech Support and have them look at your signal levels.

I would have Xfinity verify both modems are being sent the proper config file for 1200 Mbps service too.

I have the Performance Pro plan (300 Mbps) and rent a Cisco DPC3941T (XB3) gateway. I get 340 Mbps without breaking a sweat.

I would recommend using the Arris S33 instead of the XB7 gateway since it sounds like you already have a router. No sense paying the $14 modem rental charge.

Sorry for the confusion...I am only using the xfinity modem right now, but own several others to include the Arris S33.
My setup is xfinity modem (bridge mode) > Netgear 9000 router (wifi disabled) > DECO M9 plus mesh. My main rig is hardwired directly to the Netgear router and where i am getting the speeds mentioned. This rig also has built in wifi and where I get those speeds mentioned. In fact when it was first installed I hardwired my laptop directly into the xfinity modem and it was worse...I am getting better speeds with it in bridge mode.

 

[AgrFan]

You only need a modem (not a gateway) since you're using a router unless you have Xfinity Voice service.

Looks like the Netgear 9000 router max throughput is 900-938 Mbps. That may be part of the bottleneck along with the bridge mode.

https://www.smallnetbuilder.com/wir...0-smart-wifi-router-reviewed?showall=&start=2

You may want to consider reducing your Xfinity plan to 800 Mbps which would be 900+ Mbps with over-provisioning. Seems like 1200 Mbps service is overkill for your setup.

If you don't have Xfinity Voice service, return the XB7 gateway and use the Arris S33.
If you have Xfinity Voice service, return the XB7 gateway and get a Arris T25 or Netgear CM1150V modem.

https://www.surfboard.com/products/xfinity-subscribers/t25/
https://www.netgear.com/home/wifi/modems/cm1150v/

 

[sh0rty]

You only need a modem (not a gateway) since you're using a router unless you have Xfinity Voice service.

Looks like the Netgear 9000 router max throughput is 900-938 Mbps. That may be part of the bottleneck along with the bridge mode.

https://www.smallnetbuilder.com/wir...0-smart-wifi-router-reviewed?showall=&start=2

You may want to consider reducing your Xfinity plan to 800 Mbps which would be 900+ Mbps with over-provisioning. Seems like 1200 Mbps service is overkill for your setup.

If you don't have Xfinity Voice service, return the XB7 gateway and use the Arris S33.
If you have Xfinity Voice service, return the XB7 gateway and get a Arris T25 or Netgear CM1150V modem.

https://www.surfboard.com/products/xfinity-subscribers/t25/
https://www.netgear.com/home/wifi/modems/cm1150v/

While I hear what you are saying, I do need a switch of some sort...3 hard wired PCs and a server using two cables (in aggregate). The xbox can go wireless, but it is hardwired as well. I am open to getting rid of the R9000 if that is the bottle neck..thanks for that insight. I guess I just need a managed switch that I can just plug the mesh into. I dont use the xfinity voice, and as mentioned before, the arris/netgear 9000/DECO mesh on spectrum where i was worked great. I might just go back to that, but see about replacing the R9000. Thanks for the detailed response!

 

[Stugots]

Using my own hardware. I only have 300Mbit downstream, but my modem has paid for itself many times over by now. I bought it used 5 years ago and it's still working just fine.

SB6183.

 

[AgrFan]

Arris S33 > Netgear 9000 > TP-Link DECO M9 Plus mesh would be my choice.

Downgrading to 800 Mbps and returning the XB7 gateway should get you a decent managed switch.

I have a couple TP-Link unmanaged switches. They're cheap and they work fine.

Tp-Link JetStream 8-Port Gigabit Smart Switch - supports link aggregation
https://www.tp-link.com/us/business-networking/smart-switch/tl-sg2008/v3/

Arris S33 > Netgear 9000 > TP-Link SG2008 > TP-Link DECO M9 Plus mesh

I would suggest the ASUS RT-AX86U router if you decide to replace the Netgear R9000.

https://www.asus.com/us/Networking-IoT-Servers/WiFi-Routers/ASUS-Gaming-Routers/RT-AX86U/

 

[Grentz]

It's not a matter of what is sufficient though--it's a matter of what one is paying for versus what one is getting. Just because I can get by with 50Mbs doesn't mean I should be happy with getting that from a 500Mbs plan.

I cannot argue with your statement, but honestly you have no idea what my needs are from this post. However I agree that these speeds are not needed by most and rationally, maybe not even for myself. For reference, I host a server on my home network that I feel warranted this level of service. As SamirD mentioned, this disucussion is about not getting what I am paying for. I mean if I lower what I am paying for, would I get what I am getting now or even less. I am merely trying to figure out if the service gap is associated with the xfinity equipment provided.

So again, I will repeat, normal gigabit links in a PERFECT scenario (like lab perfect) max out at ~940mbps. To go above that you need to use the 2.5gb link port that the XB7 does have (its the one with the orange line) and equipment that can run at that link or higher all the way to your device. Wifi is even harder as there are protocols spec'ed at high rates, but those again are perfect world and you often won't see those in real world scenarios.

and yes, anything up at that ~gigabit link level is ridiculously fast. We run entire enterprise buildings with servers and 500+ users on links that speed and even sometimes less. Good QoS is key and understanding that most things you are connecting to won't run at those speeds anyways IE the bottleneck will be on the other end.

I get the paying for it argument, but then my answer is why pay for it? You often really will only see the benefit in doing speed tests. If you know that, have at it. You want to look at 2.5gb equipment, the other kicker is 2.5gb is a niche standard that a lot of 10gb equipment won't link at either.

 

[AgrFan]

Asus RT-AX86U router has a 2.5 Gbps LAN/WAN port and supports link aggregation of the LAN1 and LAN2 ports.

https://dongknows.com/asus-rt-ax86u-ax5700-gaming-router-review/

• Combine the LAN1 and LAN2 ports into an aggregated 2 Gbps LAN connections. This feature, available in most Asus routers, is great to host a NAS server or any devices that also feature Link Aggregation.
• Use LAN1 as the game port. A wired device connected to this port will automatically get prioritized for online games.
• Combine the WAN port and the LAN4 port into an aggregated 2 Gbps WAN connection. This configuration works great for those having a 2 Gbps Internet connection via a modem with WAN Link Aggregation.
• When you choose to use the 2.5 Gbps port as the primary WAN port, the original WAN port now works as LAN.

 

[sh0rty]

A lot to think about and thank you for all the replies.

 

[philb2]

I'm have Comcast/Xfinity lots of "Play" and right now we have a non-X1 setup. The Motorola set top box died so I did an exchange. Issue is that my wife lost lots of recordings from PBS that are no longer available for free, so I'm looking at X1. It didn't help much that the XFinity lady at the reception desk said that non-X1 set top boxes would soon be discontinued. So I feel like she was "making me an offer I can't refuse."

With X1, any reason I can't use my perfectly good Arris Surfboard TM822R modem, all paid for. It's DOCSIS 3.0, download speeds up to 343 Mbps,, 8 download & 4 upload channels, and works with Comcast Voice. Yes, I know it's not state of the art, but it works with our Internet service, and it gives me the flexibility to upgrade easily to a mesh WiFi setup in the future.

I know that Comcast is going to charge me $5/month to use my own equpment but that's better than paying $14/month for the XFi gateway.

I have this love/hate/hate_more relationship with Comcast but I have no love at all for Verizon.

 

[wizzi01]

I'm have Comcast/Xfinity lots of "Play" and right now we have a non-X1 setup. The Motorola set top box died so I did an exchange. Issue is that my wife lost lots of recordings from PBS that are no longer available for free, so I'm looking at X1. It didn't help much that the XFinity lady at the reception desk said that non-X1 set top boxes would soon be discontinued. So I feel like she was "making me an offer I can't refuse."

With X1, any reason I can't use my perfectly good Arris Surfboard TM822R modem, all paid for. It's DOCSIS 3.0, download speeds up to 343 Mbps,, 8 download & 4 upload channels, and works with Comcast Voice. Yes, I know it's not state of the art, but it works with our Internet service, and it gives me the flexibility to upgrade easily to a mesh WiFi setup in the future.

I know that Comcast is going to charge me $5/month to use my own equpment but that's better than paying $14/month for the XFi gateway.

I have this love/hate/hate_more relationship with Comcast but I have no love at all for Verizon.

When did xfinity start charging $5 to use your own equipment? When I used my own they never charged.

 

[AgrFan]

X1 uses dedicated bandwidth. It does not use your modem. What service tier do you have? Are you getting the speed you are paying for? As long as you're getting full speed and everything works properly I'd stick with the Arris TM822R modem for now. I don't believe Comcast will activate 8x4 modems anymore. You should consider upgrading to a newer modem soon. Unfortunately, there aren't many Comcast Voice modems available. Most of them are way too expensive. I rent a XB3 from them and pay the $14 charge. I figure if it dies it's their problem.

Comcast is charging you $5/month to use your own equipment? That doesn't sound right. I'd ask them if they would still charge you if you were using a newer modem. Charging customers for EOL modems may be a new way to get older equipment off the network.

Yeah, I despise Verizon also. Had three customer service phone reps berate me about keeping my POT landline many years ago. Got forced into buying two iPhones at a Verzion Wireless store to get a deal on a single phone. Switched to Comcast Triple Play and never looked back. I've been a customer for 28 years now. I live outside Philly. So, it's pretty rock solid. When I do have issues it usually turns out to be a problem on their network. But that's pretty rare.

 

[philb2]

X1 uses dedicated bandwidth. It does not use your modem.

How can that be? My modem serves Internet, plus Cable plus VoIP and now Home Security. Does X1 bandwidth use a satellite dish? J/K?

What service tier do you have? Are you getting the speed you are paying for? As long as you're getting full speed and everything works properly I'd stick with the Arris TM822R modem for now. I don't believe Comcast will activate 8x4 modems anymore.

What do they activate now? Docsis 3.1 only?

Is there a possibility that Comcast will simply deactivate my modem, forcing me to get a newer model. I like their tech support, especially the second- and third-level, but I really hate their pricing

You should consider upgrading to a newer modem soon. Unfortunately, there aren't many Comcast Voice modems available. Most of them are way too expensive.

I know. I saw one on Amazon for like $250.

I rent a XB3 from them and pay the $14 charge. I figure if it dies it's their problem.

Comcast is charging you $5/month to use your own equipment? That doesn't sound right. I'd ask them if they would still charge you if you were using a newer modem. Charging customers for EOL modems may be a new way to get older equipment off the network.

I saw that somewhere in a thread about X1 service. I forget the specific thread. It sure makes the economics of "buy your own" much worse.

Yeah, I despise Verizon also. Had three customer service phone reps berate me about keeping my POT landline many years ago. Got forced into buying two iPhones at a Verzion Wireless store to get a deal on a single phone. Switched to Comcast Triple Play and never looked back. I've been a customer for 28 years now. I live outside Philly. So, it's pretty rock solid. When I do have issues it usually turns out to be a problem on their network. But that's pretty rare.

In places like NY, ex-Bell Atlantic, Verizon is dominant. But I have a relative who lives in Manhattan where the co-op building switched to RCN. And the cousin is very happy with RCN.

 

[AgrFan]

My understanding is X1 cable boxes use dedicated bandwidth (coax) for the channel guide, on-demand streaming, DVR, etc. Internet and Voice (separate VOIP channel) use the modem. I don't have Home Security but I would expect it to use the modem also.

Comcast should be able to activate D3.0 and D3.1 modems that are approved for use on their network. Arris TM822R modems are approved for speeds up to 100 Mbps. They shouldn't deactivate your modem without first letting you know. If for some reason you get deactivated by mistake it may be a hassle to get reactivated if your speed tier is higher than 100 Mbps. I've read several threads with claims that Comcast wants to get rid of 8x4 modems. Not sure if that's true.

What speed tier do you have? Anything higher than 300 Mbps would require a new modem. I have Performance Pro (300/10). I'm getting 340/12 with over-provisioning.

You can use this website to view the list of approved retail devices at your location and for your speed tier.
https://www.xfinity.com/support/devices

I've always used Arris/Motorola SURFboard modems. Any of these Arris modems would be a good replacement.

ARRIS SURFboard SBV2402 (24/8, DOCSIS 3.0) - Up to 600 Mbps
https://www.surfboard.com/products/xfinity-subscribers/sbv2402/

ARRIS SURFboard SVG2482AC (24/8, DOCSIS 3.0, AC1750 wireless router) - Up to 600 Mbps
https://www.surfboard.com/products/xfinity-subscribers/svg2482ac/

ARRIS SURFboard SBV3202 (32/8, DOCSIS 3.0) - Up to 900 Mbps
https://www.surfboard.com/products/xfinity-subscribers/sbv3202/

ARRIS SURFboard T25 (32/8 + 2/2 OFDM, DOCSIS 3.1) - Up to 900 Mbps
https://www.surfboard.com/products/xfinity-subscribers/t25/

DOCSIS 3.1 modems are more future proof since they support gigabit speeds. If you don't need gigabit speed then you should be fine with a DOCSIS 3.0 modem.

 

[philb2]

You can use this website to view the list of approved retail devices at your location and for your speed tier.
https://www.xfinity.com/support/devices

I don't think any of these modems are on Comcast's approved list.

I've always used Arris/Motorola SURFboard modems. Any of these Arris modems would be a good replacement.

ARRIS SURFboard SBV2402 (24/8, DOCSIS 3.0) - Up to 600 Mbps
https://www.surfboard.com/products/xfinity-subscribers/sbv2402/

ARRIS SURFboard SVG2482AC (24/8, DOCSIS 3.0, AC1750 wireless router) - Up to 600 Mbps
https://www.surfboard.com/products/xfinity-subscribers/svg2482ac/

ARRIS SURFboard SBV3202 (32/8, DOCSIS 3.0) - Up to 900 Mbps
https://www.surfboard.com/products/xfinity-subscribers/sbv3202/

ARRIS SURFboard T25 (32/8 + 2/2 OFDM, DOCSIS 3.1) - Up to 900 Mbps
https://www.surfboard.com/products/xfinity-subscribers/t25/

But if if Comcast would support it, this is the modem I would get.

DOCSIS 3.1 modems are more future proof since they support gigabit speeds. If you don't need gigabit speed then you should be fine with a DOCSIS 3.0 modem.

Thanks. Makes sense

BIG EDIT:

I was wrong. I mis-set the filters. the T25 is supported

https://www.xfinity.com/support/devices#details

 

[AgrFan]