Yup, it was a DNS problem, mixed with a little DHCP problem (I think - wireless computers were jumping from 192.168.X.X IP addresses to 169.254.X.X IP addresses, or is that down to DNS too?).
Seems to be working fine now - I stopped fiddling at 1.30am this morning with 3 wireless laptops and...
I've recently installed a D-Link DGL-4300 router and D-Link DSL-300T ethernet modem and are having a few issues, and wondered if anyone could shed some light on them...
I followed the instructions given in both manuals to get them set up:
1. Plug phone line into modem, ethernet cable from...