In case you havent figured this problem out yet.
Netopia released a batch of the 4622-XL model routers most of which were sold to covad T1 clients that would periodicaly and for no apparent reason drop the LAN connection from the router to all connected devices. im not sure when you started haveing this problem but for quite some time Covad did not have any knoledge of this either that or werent willing to admit to it, any way when you would contact covad to report the problem they would run the usual test's and the router would check out fine so they would tell you that it was a problem on your end. The router checked out ok because it was not dropping WAN olny LAN so from what they could tell the router was functioning correctly. The olny way to fix this problem and it was olny temporary was to power cycle the modem, but like I said this olny temporarily fixed the problem. Any way if you are still haveing this problem contact covad again and tell them that your Netopia 4622-XL is frequently dropping the LAN connection and that any test they may run will not show this. with that they should have a new router at your doorstep with in about 4 hours.
and if I recall the bad batch of routers had a serial number starting with 933 or something like that. Covad now knows about this problem and will either replace your router with the same make and model just one that does not malfunction or they will swap it out for the Seimens 5940 buisness T1 gateway, At least thats what they did when my Netopia 4622-XL-T ceased to function properly.