We have just received a new wireless router from O2.

Now I cannot connect to external ssh servers when using wifi. It is fine when I use wired connection. Internet seems to work fine on either interface.

I can use ssh from other OS' over wifi (Tried putty on Windows7 and prompt on iOS).

When I go back to the old router it works fine again.

I can't see anything different in the routers other than that the old one has a WEP passkey and the new one uses WPA.
I also don't seem to be able to change any configuration on the router, other than some rudimentary port forwarding, but then this wasn't used on the old one.

Does anyone have any ideas of settings that need changing in Ubuntu or should I just send the new router back and use the old one

Ubuntu 10.04.4 LTS

Old router: O2 wireless box II
New router: O2 wireless box IV
both manufactured by Thomson