5milesbaby . . . . .
Same reformat/same Belkin router(ADSL version)/same problem, several months ago.
Like mdc, a bit puzzled by all these modems and routers. ...To repeat his question, is the Belkin ADSL 54g (presumably not, otherwise your ethernet cable would be in there)? ...Anyway, the only point I was going to make was that the start sequence seems somewhat relevant in all this, or certainly was in my case. ...Everything needs powering down and disconnecting first. ...Then (if applicable) make ethernet connection to router, phone connection to router, then turn router power on. ...Only lastly turn on computer(s). ...I got the impression some sort of router reboot or default setting is activated in this way. ...Certainly had no in luck trying to plug a live 'on' computer into the router and expecting it to reconfigure. ...Maybe similar with a modem and router in your case if there is actually a reason why they are both necessary.
Good luck.