Try booting the STB then the router.
Boot your pc and open a browser.
In the address bar type start.ntl
(It used to work for me on a pace box)
You will need your details from the welcome letter pid etc..
HTH
*Make sure you have no proxies set in your browser.
**If start.ntl does not work try..
https://autoreg.autoregister.net/start.html