What type or model l of network cable tester do I need?

My home is cat5e networked and I have the VDSL signal from the master socket fed via Ethernet to the fibre modem sitting on my patch panel, with the modem output fed to my WiFi router via Ethernet (let's call it cable 22) from the patch panel. This setup worked perfectly for years until recently when the router's broadband status light went red and showed as disconnected from the internet. I traced the fault to cable 22, which I tested with an RJ45 continuity tester which showed that all pins/wires were working fine, but clearly there's an issue with cable 22 from the patch panel to RJ45 module into which the router was plugged. I've since plugged the router into another network point and all's now fine.

What type of network tester could I use to diagnose the fault with the infrastructure cable 22 as it would seem the issue isn't the cable continuity but something else.

Edited by joconnell (Sun 03-Sep-23 11:28:40)

If you have a VDSL service at your master socket it could be connected to a modem such as the HG612 via a cable with RJ11 plugs on each end. You may be able to get a cable with an RJ45 plug on one end into the master socket but I would be surprised if you have a router or modem which has a port for VDSL that will take a RJ45 plug. A router with a RJ45 Wan port would expect the port to be connected to a ADSL/VDSL modem or fibre ONT using ethernet..

In reply to a post by joconnell:

What type of network tester could I use to diagnose the fault with the infrastructure cable 22 as it would seem the issue isn't the cable continuity but something else.

If your cable is standard Ethernet (Cat5/5e/6/6a) and uses RJ45 plugs, you could use something like this to check each of the cores in the cable is still connected.
https://www.amazon.co.uk/Network-Tester-LEENUE-Ether...

If your cable uses punch down blocks to connect to each end (for sockets, maybe in a wall, or patch panel) then you would need a short patch lead at each end. Test those separately.

You have misread the opening post, the suspect cable is RJ45 ethernet between the separate modem and the router. Although if all the internal cable pairs test as correctly wired it is hard to understand why it has failed.

Something like this: https://www.flukenetworks.com/enterprise-network/net...

Though often certain managed network switches and network cards have some cable diagnostic functionality which may be a good indicator

To be clear, it's the solid core cat5e infrastructure cable between the patch panel and network point in the house (labelled 22) that's failed despite a network tester showing connectivity on all 8 pins.

In reply to a post by joconnell:

To be clear, it's the solid core cat5e infrastructure cable between the patch panel and network point in the house (labelled 22) that's failed despite a network tester showing connectivity on all 8 pins.

To cover all the bases, have you checked the sockets into which the cable fits?

Just try re-crimping or re-terminating at both ends. If it is connected to a patch panel or socket then it could be that which has failed.

I would try looking carefully at both ends first before a cable tester because unless a rodent has decided to chew through it (in which case your table tester would clearly show a problem) it is unlikely there is a problem with the cable in the middle. From your initial description my bet would be on something at either end which has been overlooked, or, the problem lies elsewhere.

In reply to a post by joconnell:

To be clear, it's the solid core cat5e infrastructure cable between the patch panel and network point in the house (labelled 22) that's failed despite a network tester showing connectivity on all 8 pins.

So to be clear does the network point look like this?

No wrong again, the problem is not the master socket, but upstream of the modem in structured cabling to the router.

Ethernet network not phone network.

In reply to a post by Realalemadrid:

No wrong again, the problem is not the master socket, but upstream of the modem in structured cabling to the router.

If its structured cabling and the structured cabling tests OK then have they tested the patch leads.

Yes I've tested the patch leads.

Have you got any other leads that are known to be broken, that you can test against the tester?

In reply to a post by joconnell:

Yes I've tested the patch leads.

I can't understand why it wouldn't work then, structured cabling test OK, patch leads test OK, what else could be wrong?

Edited by PCJM40 (Mon 04-Sep-23 17:19:50)

Where are you located?

In reply to a post by ionic:

Something like this: https://www.flukenetworks.com/enterprise-network/net...

Though often certain managed network switches and network cards have some cable diagnostic functionality which may be a good indicator

LinkIQ are OK but they are fairly limited in the actual physical cable tests that they can carry out. They are more of a general purpose tester that give a helicopter indication whether a cable passes or fails (Ethernet speed tests) but not the underlying physical cable properties.

A much better test instrument from Fluke Networks is a DSX-5000 or DSX-8000 CableAnalyzer. This its what a decent commercial structured cabling installer will use to certify the cabling is up to standard, or indeed meets the EiA/TIA Category or ISO Class for the installed cabling.

Here is sample test page. In order for permanent cabling which has been installed to meet Cat5e (or Class D) or Cat6a (Class E) the cabling must meet certain parameters including:

- Wiremap
- Insertion Loss
- Return Loss
- NearEnd CrossTalk (NEXT)
- FarEnd Cross Talk (FEXT)
- Attenuation to Cross Talk Ratio (ACR)
- PowerSum ACR (PS-ACR)

The link could fail on any one of those aspects and it would result in an overall test fail for the installed cable. A DSX will not only tell you why it failed but where. Typically its the termination at the ends, but there could be a n issue along the length of the cable - sometimes these don't immediately manifest.

Hove you tested from the plug you plug into your router all the way to the incoming line point through all ports.

you could also check for straight through testing to see if the pins all go to the correct pins at the other end and there is no crossover or short.

In reply to a post by joconnell:

Yes I've tested the patch leads.

Your original post is contradictory. You are saying you've narrowed it down to a particular cable but then you're saying that cable has checked out as OK.

Unless it has degraded in some sort of unusual way (not enough for the basic cable to tester to pick up on it) then it is unlikely that is actually the cause.

Even if the (more expensive) cable tester does find an obscure issue, what do you hope to do about it?

Have you tried re-crimping both ends as a matter of course? This takes seconds to do and is of no cost to you.

I would re-trace all your diagnostic steps carefully and consider again what may be the issue. Consider buying a long reel of cable and bypass that structured cabling on a temporary basis. This will be much quicker and more conclusive than buying cable testers.

My guess is a simple diagnostic has been used when the tester showed all as green. Replace each part until it works - in this case presumably they used an alternate route to that cable which works whereas when using that cable it doesn't. Assuming all else is the same then it would suggest something wrong with that cable even if the tester says all is fine.