I think BT (like a lot of other internet service providers who give you equipment when you sign up) have the own 'firmware built into the equipment, difficult to work around. Sometimes it's possible to download the original firmaware and get them running as they were menat ot run by the original manufacturer - if it's BT branded equipment, it is almost certainly made by someone else and rebranded.

Yeh, I use Linksys, got one of those WRT54GC wireless compact ones, but since my laptop is bust, I only use it as a wired router (for the PC and a network hard drive).

What have BT and pelicans got in common?

They can both stick their bills up their arse.