ISP or the Modem Failing?

Mode13

Gawd
Joined
Jun 11, 2018
Messages
899
Hello all. My father complained to me that his internet has been going out for short intervals on the order of once every 20-40 minutes for the past 3 weeks. They called the ISP and were told they see no issue on their end, so it must be the modem (we assumed that's the generic first line from ISP before sending a tech).

However, I'm here playing around with it now to see what's going on. Modem in question is a modem/router hybrid TP Link Archer CR700 / AC1750. It has a long history of nasty reviews on Amazon, which was the first thing that made me believe the ISP.

Symptoms:

When it goes out, we get DNS errors in the browser. I tried running a few games of pubg and they will lag out for a good 60+ seconds, but interestingly I don't drop from the game, it just snaps back to life and teleports me around. I made a voice call on discord and could hear my buddy speaking through the dropouts, but he couldn't hear me responding, so I was thinking it might be an upstream issue.

Now i've just realized that during these short outages, 192.168.1.1 will not bring up the router, it just gives me a timed out error in the browser. I'm 99% sure the modem is dying out, but wondering if anybody who deals with modems regularly can help confirm that / provide some troubleshooting steps.

-I can't find any way to update firmware on this device
-I've tried disabling wifi and blowing a large fan right through the chassis (modem is now cold to the touch)
-I've verified these dropouts are network wide, hitting wifi and all wired devices (dad has a pfsense firewall, but I plugged my laptop directly into the modem - same issue)
-lights don't change on the modem, it stays solid with connection lights

more:
On july 11 there was a series of SYNC Timing Synchronization failure errors, but since then there is nothing in the log
 

Dreamerbydesign

Supreme [H]ardness
Joined
Feb 3, 2008
Messages
5,806
That’s a sketchy unit. I’d replace it with a separate modem and router. You really can’t go wrong. It probably needs to be replaced.

And that ip might not be the default login.
 

Mode13

Gawd
Joined
Jun 11, 2018
Messages
899
That’s a sketchy unit. I’d replace it with a separate modem and router. You really can’t go wrong. It probably needs to be replaced.

And that ip might not be the default login.

Thanks, trying to tell him to do so. He's just adamant that he does not want to waste money if he doesn't have to, modem is just out of warranty and purchased from amazon instead of provider. So I promised him I would dig in and ask around for opinions as I'm doing.

It's tough to help him since the ISP says it's the modem and the only way to verify that is with another modem.

It's definitely the default IP however, when the internet comes back up I can sign right in and dig around in the settings.. just pulled these down and upstream shots incase anybody cares to see

down.PNG up.PNG

some of the downstream signals seem a little high to me, or is that still in spec? upstream looks ok. It's been too many years since I've had to deal with this type of equipment.

Further, I've just disconnected the cable splitter from the primary connection in the back yard and went directly into that with the modem, issue persists, so that also knocks out the possibility of in home wiring being the issue.
 
Last edited:

Dreamerbydesign

Supreme [H]ardness
Joined
Feb 3, 2008
Messages
5,806
If that is the default ip, then yes that unit is garbage.

Save yourself some headache buy new stuff. A modem is cheap and any decent lower end router will do. You can find both for less than 50 bucks a pop that will last years.

But that unit is surely toast. Sounds like it’s damaged or overheating
 

Mode13

Gawd
Joined
Jun 11, 2018
Messages
899
What do you think about the Arris Surfboard line of modems? He says he prefers the modem and wifi contained into a single unit but if the combo units will be this problematic, I'll tell him tough luck.

ISP is Spectrum Internet, I believe he has 500~ download speed, existing modem is DOCSIS 3.0
 
Joined
Feb 19, 2014
Messages
580
I may have a spare Spectrum combo box. They shipped it to my father in law in error and he gave it to me for some reason. Wife is sleeping so I can't check now. If I don't respond over the weekend just shoot me a PM to help remind me.

Edit: Is there a log in the router you can check?
 

Mode13

Gawd
Joined
Jun 11, 2018
Messages
899
I may have a spare Spectrum combo box. They shipped it to my father in law in error and he gave it to me for some reason. Wife is sleeping so I can't check now. If I don't respond over the weekend just shoot me a PM to help remind me.

Edit: Is there a log in the router you can check?

thanks for offering the Spectrum combo, dad ended up ordering an Arris Surfboard SB6183.. should be arriving tomorrow.

I did check the log in the router but the last errors were from 7/11 showing two "SYNC Timing Synchronization failure errors", besides that there was nothing. I just know for sure that when the internet goes out, you also can't open the routers local admin page, which seems to indicate the entire unit is locking up for minutes at a time.

hoping the surfboard solves his problem
 

jardows

2[H]4U
Joined
Jun 10, 2015
Messages
2,200
thanks for offering the Spectrum combo, dad ended up ordering an Arris Surfboard SB6183.. should be arriving tomorrow.

I did check the log in the router but the last errors were from 7/11 showing two "SYNC Timing Synchronization failure errors", besides that there was nothing. I just know for sure that when the internet goes out, you also can't open the routers local admin page, which seems to indicate the entire unit is locking up for minutes at a time.

hoping the surfboard solves his problem
Good modem, but watch the temperatures on that - it will run hot. Early models didn't have proper heat sinks or thermal tape, so we ended up replacing a lot of them. It is just a modem, so if he is using wi-fi or connecting additional devices, make sure he has a router in place.
 

Mode13

Gawd
Joined
Jun 11, 2018
Messages
899
Thanks for the warning, will check and see if its running hot next time I stop by.

He uses a dell running pfsense out to a switch as his wired router and i put the old modem in bridged for wifi as a temporary solution - he says thats working fine.

Internet hasnt dropped out since yesterday evening when the modem was swapped!
 
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