On my wet11, the diag light never lights.

Thanks, that's reassuring to know. I gave up trying with the AC adapter I had here; the connector was too small and the connection was sometimes intermittent. The good news is that the eBay seller acknowledged he hadn't sent the proper adapter and it's in the post so I'll wait a few days

Did you fiddle with the cross over switch?

I flicked it a few times but, to be truthful, my hub can be a little flaky and I can't swear that I wasn't using one of the dodgey ports. Added to that, I know I have a few bad ethernet cables around here so I guess I need to start testing them using known-working equipment. My excuse is; I've just moved house and I ended up chucking everything (good, bad, unknown) into boxes at the last minute so I've lost all track of what's good and what's not!