What tools do you recommend for that sort of thing? I've used Firebug a bit, and I know of Fiddler but haven't tried it.
Wireshark I tried very briefly before discovering I was asking the wrong question (Wrong: "Why does this Android phone not get an IP address from the router when the Windows desktop and Linux laptop worked fine with it a moment ago"; Right: "Why is this router not working when it did a moment ago". (Answer "no idea, BT have raised a support ticket, but it seems to have got better again".))