At work, we have a basic Class C Network. The gateway/router is a SMC8013WG (stock comcast commercial cable modem), and simple unmanaged switch (HP Pro Curve 1400 24G).

The SMC8013WG is our default gateway as well as DHCP server.

Periodically, I'd say almost every other day.. the entire network will just stop responding. I won't be able to ping/see the gateway, any computers on our local network, or anything on the internet.

The only way to fix this is to unplug the Comcast cable modem, wait, and plug back in. This unfailingly fixes the problem.

But this doesn't make much sense to me.. shouldn't the network still be fine locally, since everything is plugged into the switch anyway? Why would resetting the router fix this?

Can anyone suggest anything to check to in order to narrow this problem down?

Just to be clear.. here is the basic topology:

{ Internet } -- (12.345.67.89) Comcast Cable Modem (192.168.1.1) -- Switch -- 192.168.1.2-254

P.S. Our IT guy is in about 3 hours a day every other week or so, so.. we're kind of on our own most of the time.