There are hardware cable checkers, but they're either cheap (~£20) and check just continuity and wire map faults, or can test performance but cost hundreds of pounds like the Fluke ones.

You say it's an outside cable... did you terminate it yourself? If so re-terminating might help. Are there any connection points, or damage to the cable (perhaps from birds/squirrels/mice, or tight bends, underground water-logged pipes, or some such) that could allow water ingress or intermittent shorts? Does your cable get exposed to electromagnetic interference from nearby equipment? You could also look at the PSU that comes with your switch and router; sometimes they start providing borderline power. Are both ends connected to equipment plugged into the same power supply?

The easiest is probably to temporarily relocate the PC next to the router, use a different, shop-bought known-good cable, and compare.

What is it specifically that is slow? It could be a network software issue. DNS often seems the cause of slowness for me, and messed-up routes can cause issues too, or something like a duplex mismatch or mtu problem.

[2] http://www.comms-express.com/products/microscanner2-cable-verifier-kit/?gclid=CLbcr4CWgsYCFSnkwgodo6UAgA

On 9 Jun 2015, at 08:39, Mark Rogers <mark@more-solutions.co.uk> wrote:

Are there any tools that would help detect/locate cabling issues?

I suspect I have a dodgy connection on a length of cable that runs
outside my house between my (Ubuntu) desktop and my (OpenWrt) router.
There's a gigabit switch between the two although I could probably
reroute cables enough to bypass that if necessary.

My old desktop has been generally slow for a while, and now that I've
replaced it with a new PC, with a fresh install to a new SSD, it's
(very disappointingly) no better. Given that most of what I use it for
uses the network in some way I'm thinking that's my next place to
look.

Mark
--
Mark Rogers // More Solutions Ltd (Peterborough Office) // 0844 251 1450
Registered in England (0456 0902) 21 Drakes Mews, Milton Keynes, MK8 0ER

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