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Faulty Ethernet cable?

wheeshty — Sun, 16 Feb 2025 18:19:30 GMT

Hi,

I’ve just got my new broadband router set up in a half finished new build (it’s dry at least) and I’m trying to run two Wi-Fi ‘extenders’, 1 to my office and 1 to my caravan.

The office set up is running fine - a 40m run of cat5e cable from the Ethernet port in the router to the wan port on my old 4g router so the office has Wi-Fi.

The problem is the caravan - I fitted RJ45 ends to a 100m length of cat 5e cable, tested it with a 9V remote and master tester set, and it seemed fine, all 8 lights shone green. I plugged it into the same wan port of a 4g router in the caravan and there is no signal whatsoever - my device can connect to the 4g router but there is absolutely no bandwidth/transfer of data.

The cable is not shielded though runs in it’s own underground duct, but in the same trench as a SWA cable in a different duct so over the length of the run the 2 cables are probably pretty close but never touching - however I would expect some data/bandwidth/technical term? to get down the cable rather than nothing at all.

I have tried switching routers and Ethernet ports but to no avail.

Any ideas how I should proceed to solve the issue and get internet to the caravan router?

Thank you.

Re: Faulty Ethernet cable?

WSH — Sun, 16 Feb 2025 18:25:46 GMT

If you are just using the old routers as wireless access points, it's lan port to lan port not wan port. Also 100m for cat 5e is pushing it. The 100m spec figure is under lab test conditions with a perfect install & with top quality cable. Techies usually don't push beyond 85m

Re: Faulty Ethernet cable?

WSH — Sun, 16 Feb 2025 18:27:54 GMT

I take it the IP addresses are all in the same network? Probably easiest to disable the DHCPs in the two satellite routers.

Re: Faulty Ethernet cable?

wheeshty — Sun, 16 Feb 2025 18:33:26 GMT

Thank you for your replies.

The WAN port is also a LAN port so that should be ok.

Not sure how to disable DHCP. The same model of router works ok in the office, 40m away, but neither of the 2 satellite routers work at the longer distance.

Perhaps I’ll try a shielded CAT6 cable over the 100m and see if that’s any better.

Re: Faulty Ethernet cable?

WSH — Sun, 16 Feb 2025 18:44:26 GMT

It's unlikely to make any difference as I doubt that's the problem*. The dual LAN/WAN ports don't usually switch automatically, so make sure it's in LAN mode. If all three routers have DHCP turned on they'll probably be stuck arguing about who has what address. You need the one DHCP in a network. (It is technically possible to have more than one but let's not get complicated).

*Just to clarify. It doesn't suddenly stop at 100m, it just that the performance goes to ....

Re: Faulty Ethernet cable?

TimCurtis — Mon, 17 Feb 2025 14:48:44 GMT

When setting up the problem router to test out the cat5e cable just bring it to the main router and connect it via a known working cable. If it then works it's a cable fault.

Re: Faulty Ethernet cable?

pddco — Mon, 17 Feb 2025 15:25:14 GMT

Could you not simply connect the caravan end of the cable to a PC just to check the cable? Or even an Ethernet switch with some activity / link lights. And does the tester you’ve used identify crossed / incorrect wiring? I’m assuming it must do but very odd that you’re getting no data at all. Just a thought.

Oh just as an aside. The system has for some reason labelled me an expert. No idea why. I know stuff, and perhaps a bit more than the average. But expert? Perhaps it’s based on the number of replies. Take care out there.

Re: Faulty Ethernet cable?

wheeshty — Mon, 17 Feb 2025 15:41:28 GMT

Thank you all.

PC connected directly to end of caravan cable gets no data and caravan router works in office, so it looks like it’s the cable - even though my cable tester blinks green for all 8 wires within that cable.

I’ll try new rj45 connectors and if no joy I’ll pull through another slightly better cable and try again.

Ill report back next week.

Thanks.

Re: Faulty Ethernet cable?

WSH — Mon, 17 Feb 2025 17:08:19 GMT

The trouble with those Wire Map testers (as they are known) is that they tell you if there is a connection but nothing about the quality of the connection. (You need a Certification tester for that. A very expensive bit of kit).

It could be a lot of things. I've seen a case before where an enthusiastic apprentice squeezed the crimp tool too hard. Cable looked and tested fine but the pins had been pushed in a bit too far to make a good connection in the socket.

On a more serious note, I didn't recognise "SWA cable" when you originally mentioned it and I've since looked it up. Two points: While twisted pair cable is pretty good at rejecting interference at 230V it's not perfect & a 100m is a hell of long parallel run. More importantly, I'm not a sparky but I'm pretty sure the safety regs would prevent running network cable and mains down the same duct. That arrangement may not be safe.

Re: Faulty Ethernet cable?

wheeshty — Mon, 17 Feb 2025 17:15:14 GMT

hi, I’ll try again with the rj45 and a gentler touch.

the power cable and cat5e cable are in separate ducts but running in the same trench so they will not be in contact but may run fairly close to each other for some/all of the way.

Re: Faulty Ethernet cable?

WSH — Mon, 17 Feb 2025 17:20:26 GMT

Ah, good. As I said, I looked up SWA cable later and was a bit concerned they were in the same duct.

I’m retired and it’s been a long while but I seem to recall the recommended minimum separation for unshielded and power cables is 8” and for shielded is 2”. A lot depends on the voltage though and I think that was for above 415V.

Re: Faulty Ethernet cable?

WSH — Mon, 17 Feb 2025 17:46:08 GMT

A further thought has just occurred. I take it that cable has been wired to TIA 568B standard? A straight through or crossover should both work with modern kit.

It's very strange that it tests OK but you're not getting a connection at all.

Re: Faulty Ethernet cable?

pddco — Mon, 17 Feb 2025 17:47:13 GMT

@WSH If it’s SWA power cable then wouldn’t the armour strands be bonded to the CPC (earth) and therefore perhaps acting as a basic screen of some sort in any case? Hopefully the OP will get it sorted after reterminating.

Re: Faulty Ethernet cable?

WSH — Mon, 17 Feb 2025 17:52:48 GMT

Interference from mains would screw the performance up, it wouldn't stop it working. I was more concerned about the safety aspect but if they are in separate ducts it should be fine.

Re: Faulty Ethernet cable?

SwanseaMick — Tue, 18 Feb 2025 15:20:49 GMT

Have you connected the cable correctly?
It may seem a silly question (I don’t know your level of expertise), but as the cable is in twisted pairs, it is important that the correct pairs go to the correct pins to avoid distortion. It is not case of pair 1 goes to pins 1&2, pair 2 goes to pins 3&4 etc

Your end to end tester may simply be telling you that pin 1 is connected to pin1, and pin2 to pin2 etc, it may not be telling you if you have crossed pairs.

I apologise if I’m stating the obvious

Re: Faulty Ethernet cable?

WSH — Tue, 18 Feb 2025 17:06:27 GMT

I did ask earlier if it is wired to 568B.

Or to clarify:

Pin Colour

1 Orange&white

2 Orange

3 Green&white

4 Blue

5 Blue&white

6 Green

7 Brown&white

8 Brown

Re: Faulty Ethernet cable?

wheeshty — Tue, 18 Feb 2025 22:53:20 GMT

Hi yes I used this wiring schedule.

I’m away on holiday for a week now so I will change the RJ45 ends when I get back and report how it goes.

Thank you for the help

Re: Faulty Ethernet cable?

wheeshty — Wed, 12 Mar 2025 20:16:17 GMT

Hi all,

Thank you all for the helpful advice.

Although I'm slightly ashamed to admit it, I must come clean -

An electrician friend replaced the RJ45 ends today and lo' and behold the cable works now!

Best wishes

Re: Faulty Ethernet cable?

WSH — Wed, 12 Mar 2025 20:37:25 GMT

Yes, doing it well is a bit more tricky than most people realise.

Good of you to put your hand up though. All's well that ends well.