Ethernet cable questions and more!

biggles

2[H]4U
Joined
Jul 25, 2005
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2,075
1. I have old ethernet cables with no labeling on them. So I cannot tell if they are cat5, cat5e, or cat6. If an ethernet cable is not labeled, is it correct to assume it is cat5? Are there other ways to identify ethernet cable type besides text on the cable itself?
2. I believe ethernet cables are supposed to be backward compatible. So that if I used a cat5 cable it would work but would cap bandwitch at Mbps. But I recently installed a TP-Link ax1800 wifi 6 router and it would not connect to the internet when using the cable to link the cable modem and router (it did work when using the cat5e cable that came in the box with the ax1800). So, does this mean in some cases ethernet cables are not backward compatible?
3. Testing internet speeds on a Roku for the wifi 6 network vs wifi 6 network using wifi extender. The extender gives higher signal strength but lower speed. I am guessing this is because the wifi extender is only wifi 5, correct? If appears that the wifi extender is obsolete on a wifi 6 network.
 
Joined
Dec 1, 2011
Messages
978
1. I have old ethernet cables with no labeling on them. So I cannot tell if they are cat5, cat5e, or cat6. If an ethernet cable is not labeled, is it correct to assume it is cat5? Are there other ways to identify ethernet cable type besides text on the cable itself?

I'd agree it's probably Cat5. No good way to really tell without a Fluke or like tester that'll cost many thousands of dollars.


2. I believe ethernet cables are supposed to be backward compatible. So that if I used a cat5 cable it would work but would cap bandwitch at Mbps. But I recently installed a TP-Link ax1800 wifi 6 router and it would not connect to the internet when using the cable to link the cable modem and router (it did work when using the cat5e cable that came in the box with the ax1800). So, does this mean in some cases ethernet cables are not backward compatible?

It may be a Cat5 or batter cable, but maybe it's not actually wired for ethernet? Verify that it's 568A or 568B.

Anyways, cables are cheap and it's rarely worth dealing with problem ones. I always toss them at the first sign of issues.


3. Testing internet speeds on a Roku for the wifi 6 network vs wifi 6 network using wifi extender. The extender gives higher signal strength but lower speed. I am guessing this is because the wifi extender is only wifi 5, correct? If appears that the wifi extender is obsolete on a wifi 6 network.

How much slower? Any slowdown may be more on the design of the extender itself, especially if it's an older or cheaper single-band unit that simply repeats the signal on the same channel.
 

pendragon1

Fully [H]
Joined
Oct 7, 2000
Messages
26,322
1. I have old ethernet cables with no labeling on them. So I cannot tell if they are cat5, cat5e, or cat6. If an ethernet cable is not labeled, is it correct to assume it is cat5? Are there other ways to identify ethernet cable type besides text on the cable itself?
2. I believe ethernet cables are supposed to be backward compatible. So that if I used a cat5 cable it would work but would cap bandwitch at Mbps. But I recently installed a TP-Link ax1800 wifi 6 router and it would not connect to the internet when using the cable to link the cable modem and router (it did work when using the cat5e cable that came in the box with the ax1800). So, does this mean in some cases ethernet cables are not backward compatible?
3. Testing internet speeds on a Roku for the wifi 6 network vs wifi 6 network using wifi extender. The extender gives higher signal strength but lower speed. I am guessing this is because the wifi extender is only wifi 5, correct? If appears that the wifi extender is obsolete on a wifi 6 network.
1 - prob cat5
2 - it should work, just possible lower speed.
3 - correct but not really obsolete just slower, 54g is obsolete.
 

jerry8169

Limp Gawd
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Nov 1, 2020
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142
Testing internet speeds on a Roku for the wifi 6 network vs wifi 6 network using wifi extender. The extender gives higher signal strength but lower speed. I am guessing this is because the wifi extender is only wifi 5, correct? If appears that the wifi extender is obsolete on a wifi 6 network.
Where is your extender placed? If it's in the same room that your wireless device is that you are trying to get better signal to, then it won't improve as it's only extending the signal it sees, which would be the same one your device in that room already gets. It would show a stronger signal strength because the extender is broadcasting in that room. As a general rule of thumb, you want to place the extender approximately halfway between your router and where you want the better signal, this gives the extender a decent signal to pick up and rebroadcast.
 

toast0

[H]ard|Gawd
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Most ethernet cables have a label on the jacket every yard or so (if not more often); so it's a little surprising it's totally unlabeled. Could be cat3 of course. I agree with BlueLineSwinger, if it's giving you trouble toss it, but I also like debugging stuff, so...

What happens when you plug it in? Do you get a link light, but it doesn't work, or no link light? If it's wired properly for ethernet, you should get a link light; if you're not getting that, it's probably some weird pinout. If you get a link light, but it doesn't work, it could be the cable isn't up to the speeds. Ethernet negotiates speeds based on what the two ends are capable of, not based on what the intermediate wire is capable of; which can easily lead to sadness: ex old janky 100 foot cat3 cable with only two pairs wired will work fine for negotiation (it runs at 1 Mbps), but could negotiate to 1Gbps which won't work without all four pairs, and likely won't work on 100 feet of cat3 with all the pairs either. Some drivers will fallback to a slower speed, but that's something extra they added to the driver, not part of the spec.

Most wifi extenders are also going to drop your speed roughly in half, because they usually use the same spectrum for sending and receiving, which doesn't work so well. There's some dual band models, which can be more helpful; and you might have some perfect conditions sometimes where putting it about halfway between the access point and the device lets your device communicate at a faster rate with the extender and the extender communicate at a faster rate with the base, and anywhere there's a big blockage in the direct line of sight between the base and the device. Anyway, these things suck; if you can, bring wired ethernet to the device, or bring wired ethernet closer to the device and add another access point; or maybe your new base is fine by itself.
 

TheSlySyl

[H]ard|Gawd
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May 30, 2018
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I know my router can "sense" what ethernet cables are attached to it and it shows up right on the main router page.

1615445879787.png


Maybe yours would show the same?

Also, if using a cable doesn't work at all, it's likely because the cable itself has gone completely bad, nothing to do with what CATegory it is.
 

biggles

2[H]4U
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The unlabeled ethernet cable was working before upgrading a TP-Link AC1750 router. But it would not work on the new AX1800 wifi 6 router. Also, the network speed was just under 100 Mbps on the old network and around 170 Mbps on the new network. I am thinking the 100 Mbps cap was due to the cat5 bandwidth limit. So in other words if I had been using a cat5e or cat6 cable on the old network I would have seen up to 170Mbps.

Also, here is the wifi repeater device:
https://www.amazon.com/gp/product/B07N1WW638/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
 

bman212121

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Aug 18, 2011
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Sounds like the non working cable is bad. As for the type, you can figure out what cable it is by cutting it open and looking at the number of twists per inch. There is no hard fast rule, but if it's less than 2 twists per inch it's probably 5 or 5e and if it's more than that it's probably 6 or 6a. There are some other differences like wire gauge and shielding that you'll probably find on newer cables as well. Obviously you don't want to do this if you want to use the cable, just pointing out that there is a way to tell. I'm going to assume we're talking about a short patch cord that came with a router as those are the type of the cables that are most commonly void of any print on the jacket.

As for Cat3, I've only seen it once in my life, and it was abandoned cable in a wall. It was used for a short period of time from like the late 80s through the 90s (I don't know exact dates, I found a source that claims it became a standard in 1990 but the oldest ISO document I've found was from 1995) Most commonly cat3 is only going to have 4 wires in it, and not 8. So simply looking at the end and seeing 8 wires means there is a good chance it's not cat3. So it's highly unlikely you're going to find it in the real world because even during it's time it wasn't necessarily the most common type of cable. Thicknet or thinnet over coax was probably as widely used and I've seen multiple implementations of early networking that were either DB9 or DB25 serial connections as well.

All of that said if it has 4 pairs of wires it can probably do 5 - 10 gig if the cable is like 5 feet long. The reasoning for the twists has more to do with crosstalk from other wires over long distances than it really does about the wire itself. The spec is based around 100M of cable that is bundled together with like a hundred cat5 cables all stacked on top of each other like you would find in a cable tray. What you're doing at home I wouldn't be surprised if you took 2 flat wire phone cables and punched them down to some keystones you'd still have no issues pulling gigabit speeds out of it. I've successfully ran 450' of cat5e at gigabit speeds, so take the specs as the minimum they are rated for, not the fastest they could actually run. (Hence why 2.5 gig and 5 gig became standards)

The wire can influence the link speed in that 10 or 100mbit only requires pins 1,2,3,6 to be active. Gigabit or higher requires all 8 pins to be live. But otherwise the cable you plug it isn't going to dictate the link rate, the network adapters at either end will decide that regardless of what cable is between them provided all the wires exist. If the cable is bad you'll just end up with intermediate issues (like what you're seeing) but it won't vary the link rate based upon signal quality as that's not a feature of 802.3. (Someone insert some oddball "actually" here)
 
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biggles

2[H]4U
Joined
Jul 25, 2005
Messages
2,075
I know my router can "sense" what ethernet cables are attached to it and it shows up right on the main router page.

View attachment 337750

Maybe yours would show the same?

Also, if using a cable doesn't work at all, it's likely because the cable itself has gone completely bad, nothing to do with what CATegory it is.
Thanks to this advice I was able to determine the speeds of connected devices on the new ax1800 router. Questions about this powerline networking setup:
https://www.newegg.com/d-link-dhp-p339av/p/1A7-001C-00077

This D-Link product says max speed of 500 Mbps. But the ethernet data rate is only 10/100, so it seems it would be capped at 100 Mbps, correct? The router settings page 192.168.0.1 confirmed the D-Link product to be capped at 100 Mbps. If true I do not understand why this product would be advertised as 500 Mbps speed since that would be impossible.

Also, I ran speed tests on the other end of the powerline network and got around 42-44 Mbps, way lower than the 100 Mbps expected. But since it is only used to connect to a PS4 maybe that is adequate speed. Running a speedtest on the PS4 on the powerline network showed speeds of about 27 Mbps. Since 42-44 is bigger than 27, is it correct to say the powerline network is NOT bottlenecking the PS4 downloads?

Would there be any performance boost to installing a wired ethernet jack in the house to connect to the PS4? We are also considering getting a Roku Ultra in the future and using a wired connection on it. But again I wonder if the Roku would benefit from wired ethernet. The Roku currently gets around 24 Mbps in wifi, and perhaps that is sufficient. In case it matters to the discussion, our Comcast internet gives about 170 Mbps down.
 

TheSlySyl

[H]ard|Gawd
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It's cause the Wifi has a theoretical "max" of 500mpbs. It's mostly deceptive marketing and bullshit. Sadly.

I don't know enough about powerline networking to be able to answer that, i do know that it is heavily determined by the quality of the wiring in your house. I will say that having a wired connection for any stationary video device that you're expecting a lot of 4k out of is definitely a huge boon. Partially for reliability, but mostly to cut down on wifi interference.
 
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