My first network - made up of two boxes - called upstairs and downstairs. Upstairs is the beefy machine with a modem which has all the software I could need. Downstairs is a older (p200) basic machine which has fvwm and xfree installed with ssh client.

They are connected via a cross-over wire (no hub) with static IP addresses (10.1.1.1 and 10.1.1.2) and work fine (using ping and ssh) until the beefy machine connects to the net with the modem. Then neither of them can talk to each other.

Is there a way I can still ssh into beefy whilst it's using it's modem to connect to the net?

advTHANKSance

check your routing table while connected and not connected as well as the ip address of your NIC.