Is the 'modem' a usb device direct connect or actually a router and modem?

Wow uses insignificant bandwidth to call it 'overloaded', the spikes are when character load and when zoning, but those are pretty mute if your not in a full raid or similar.

I would look to why your running cache\wdb\* shared for all the accounts, but if you say the modem is actually resetting I assume heat or whatever is hurting it.