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Home internet - CAT-5e wiring question

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 LastBoyScout 19 Jul 2021

I'm sure someone will know this - Google is a bit of a minefield.

Home setup was as follows, and was working fine - fibre broadband:

BT router -> Cat-4 cable into wall port -> Cat-5e internal wiring -> Cat 5e cable into BT hub -> Cat-4 cable into BT TV box.

We had a local BB outage, now fixed, but I ended up phoning BT last week because BB speed had drastically reduced (on wifi - we don't use wired for the laptops). Their advice was to put the hub as close to the router as possible and connect it using Cat-5e, so I now have the following:

BT router -> Cat-5e cable into BT hub -> Cat-4 cable into wall port -> Cat-5e internal wiring -> Cat 4 cable into BT TV box.

Wifi speed is much better, but the BT box won't now connect to broadband. I've tried testing the various components with my laptop and the issue seems to be the internal cabling not connecting.

So, finally, the question - does the hub -> wall port cable need to be Cat-5e, or all the connections need to be Cat-5e? I didn't think that it should be an issue, except that it would be a bit slower with Cat-4 in the mix and it was working previously.

I don't have any test equipment to see if the internal wiring has developed a fault, but it would seem unlikely, as all I've done is change a couple of plugs. I've also only got 1 Cat-5e cable, or I would have already tried that - I might try and borrow a couple to test the theory.

Thanks,

 robhorton 19 Jul 2021
In reply to LastBoyScout:

Cat4 is ok for 100M but not 1G ethernet - it's possible the router / hub / tv have negotiated up to 1G but are getting errors due to the Cat4. Any Cat4 cable now has got to be pretty old anyway - I would start by spending a few quid on some Cat5e ones. If you're still having problems you can have a deeper look at the internal wiring etc.

 two_tapirs 19 Jul 2021
In reply to LastBoyScout:

This sounds like a real cop-out response, but have you powered down the BT TV box for a couple of minutes? Years ago when we had sky, if we had a network or BB problem, the Sky HD box would retain the old IP address it had been assigned, whilst the Sky BB router had issued a new IP address.  A 2-3 minute moment of no power at all to the Sky HD box solved the problem; the Sky HD box got it's IP address via DHCP, but there was some bug/quirk which meant that it didn't pick up the new IP address

In reply to LastBoyScout:

Are the ends of your internal wiring both terminated to the same standard (T568A vs T568B).  I believe that some equipment will automatically compensate if the terminations are mixed, but others don't.  i.e. your hub may have been automatically correcting for a wiring error when it sat before the TV box, but now it's moved, the TV box can't deal with the error.

 LastBoyScout 19 Jul 2021
In reply to two_tapirs:

Yep - done all the on/off stuff, several times with different configurations.

 LastBoyScout 19 Jul 2021
In reply to Sam W:

Yes - that's sort of what the lady @ BT was alluding to when I phoned originally about the slow speeds. She wasn't technical, but suggested the fix to the broadband outside might have tripped something inside that was working but now wasn't, but couldn't explain why.

 LastBoyScout 19 Jul 2021
In reply to robhorton:

Right - ignore that.

I've just checked and it seems that ALL the cables are Cat-5e, the only difference is one has red ends and the others have yellow ends. Lady at BT said there was a difference between them, which lead me to assume the yellow ones were cat-4.

I'll have another play later with the order of the cables...

Post edited at 19:26
 Philip 19 Jul 2021
In reply to LastBoyScout:

Presumably you can plug your laptop in, you just don't. Maybe you could use it to run some network analysis and see what speed and packet loss you're getting at each point.

The hub closest to the TV is rubbish, if they're not in the same room they give you powerlines. I'm currently WFH with powerline across two different sides of the consumer unit and still getting decent performance.

Put laptop straight onto hub with cable, if performance is bad phone them back. You have to put up with their patronising questions about trying the test port etc, but you should get someone doing something eventually.

 mutt 19 Jul 2021
In reply to LastBoyScout:

>Wifi speed is much better, but the BT box won't now connect to broadband.< 

go into settings in on your BT TV Box and find the DHCP settings or IP settings. Your objective is to renew your IP address. Your BT router is in all likelyhood providing a DHCP service that provides IP addresses to all your connected equipment. If BT TV has an IPAddress it won't necessarily request a new one but your router might not have the same address registered. Renewing the lease will sync up the two systems.

If that doesn't work then its most likely badly seated cables. Make sure they are all in the right Lan/Wan sockets and all click into place. there is most likely an led on each one to show green or orange if there is a connection.

 SouthernSteve 19 Jul 2021
In reply to LastBoyScout: A couple of ideas

Perhaps buy a small (cheap) cable tester. 

You could give some of your internal items manual IP addresses and see what the speed is like between them.

Also is there a hub or switch in this arrangement or are you using the BT router as the hub?

In reply to mutt:

Except that LBS says he'd tested everything with a laptop and identified the internal network wiring as faulty.

Pure speculation: The internal wiring has been faulty for a while, the TV box had fallen back on a WiFi connection to the hub. Now the hub has been moved, the TV box is out of range.

 LastBoyScout 20 Jul 2021
In reply to AndyC:

> Except that LBS says he'd tested everything with a laptop and identified the internal network wiring as faulty.

Further testing reveals that internal wiring might be ok, but only borderline connecting - that was using the yellow cables for every connection.

> Pure speculation: The internal wiring has been faulty for a while, the TV box had fallen back on a WiFi connection to the hub. Now the hub has been moved, the TV box is out of range.

No - hub -> TV box was wired and TV box does not have wifi. I'm going to put it all back as it was and see if it comes back...

 Jack 20 Jul 2021
In reply to LastBoyScout:

BT router -> Cat-4 cable into wall port -> Cat-5e internal wiring -> Cat 5e cable into BT hub -> Cat-4 cable into BT TV box.

Is the problem in the wall port. Before your  hub was in front of it, now behind it. I'm curious as to what the wall port is / does. Is it doing the job of a switch?

 SouthernSteve 20 Jul 2021
In reply to LastBoyScout:

When you say BT router and BT hub, I have always with the supplied equipment just had one device for both functions. Your set-up does not sound standard or am I missing the point!

In reply to LastBoyScout:

Telecoms 101 - you need to prove the fault into a particular bit of the network, starting at 'layer 1' - the physical layer. Plug a laptop into the hub's ethernet port you're using for the TV box to prove that the port works, and what speed it's running at. If that's good, then repeat the process with another ethernet cable (the one from the TV box to the wall) to find two good cables. Then plug the laptop into the port using those two good cables and the house wiring. If that works then you know the router, hub, hub port, cable into the wall, internal wiring, and cable out the wall are all good and the problem is going to be either the TV box, or the interaction between it and the hub. That interaction is probably going to be a duplex/speed/auto-negotiation problem (try forcing the hub to use full duplex / 100mb) or DHCP IP addressing problem.  If the internal wiring works but is slow try running a continuous ping from the laptop to the hub or a device connected to it to see if you're getting packet loss. If so it would appear to be an issue with the internal cabling, most likely corrosion in the terminations.

In reply to SouthernSteve:

> When you say BT router and BT hub, I have always with the supplied equipment just had one device for both functions. Your set-up does not sound standard or am I missing the point!


Fibre tends to have it's own NTU (network terminating unit) which converts the incoming fibre to an ethernet presentation.

 elsewhere 20 Jul 2021
In reply to LastBoyScout:

Seems unlikely it is missing, but you've not mentioned it so here goes.

Assuming you are "normal" ADSL broadband, do you have an ADSL Filter?

See URLs for what it looks like

https://www.amazon.co.uk/ADSL-Filter-Broadband-Plusnet-Vodafone/dp/B004AEYHNI

https://www.toolstation.com/adsl-signal-filter/p78434 

Filter can also be built into master socket (phone line coming into house).

https://www.amazon.co.uk/Openreach-Telephone-Master-Socket-Faceplate/dp/B07NX2KC8Y

I would expect to see something like... 

Master Socket -> ADSL Filter -> ADSL Modem(1) (home hub combines ADSL modem, ethernet* & wifi) -> Ethernet wiring -> WAN (ethernet) input on second BT hub(2) -> Ethernet wiring -> BT TV Box

*plug laptop in here using ethernet cable, disconnect outgoing ethernet to second BT hub and anything else then do speed check. Assuming both BT hubs are ADSL Model/Wifi/Router swap BT Hubs and try the same thing.

(2)why do you need this, are you using it as a wifi booster or to have multiple wired connections? Is poor wifi due to laptop connecting to (1) rather than (2) which is closer?

Switch off the second BT hub when doing this (no wifi interference) and try wifi with laptop next to master socket & BT Home Hub (1).

You could also connect laptop to hub(2) with wire & compare speed.

What are model numbers of the two BT devices?

 kathrync 20 Jul 2021
In reply to LastBoyScout:

> I've just checked and it seems that ALL the cables are Cat-5e, the only difference is one has red ends and the others have yellow ends. Lady at BT said there was a difference between them, which lead me to assume the yellow ones were cat-4.

As someone else alluded to, the difference here could be cable terminations (T568A vs T568B). Essentially, there are two ways of setting up the wiring when you attach cable terminations, so cables can either have A terminators, B terminators or "crossover" (A at one end, B at the other).  If you have the wrong one in the wrong place you can "lose" the signal.  Usually in a small domestic network, there is no requirement to use both types, just pick one or the other and stick with it.

Another consideration is if your "BT router" and "BT hub" are both trying to route network traffic. Usually in a setting such as you described, the one nearest the input would be put into a mode where it just converts the incoming signal to ethernet and passes it along to the second one which manages and routes traffic. This is sometimes called "modem mode" or "passthrough mode". Having both trying to route traffic if they aren't configured correctly could be causing conflicts. I'm assuming this is not the case as you had it working previously, but it is worth checking.

 SouthernSteve 20 Jul 2021
In reply to Toerag:

I have BT fibre (Fibre 2) and it is not fibre into the house, but telephone wire to a box which splits the telephone from data without need for a ASDL filter or similar. In the original set-up the BT 'box' was modem, router and 4 port hub, although as we have 2 lines from different providers coming in this has been removed and a more independent set-up installed which uses PPOE on that line.


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