server admin cannot find host

I am running mac osx server, snow leopard. It ran fine until just recently. Suddenly Server App is unable to find the host it runs on.

I enter the hosts IP address on the local network, log in with my administrator username and password, and the system comes back telling me

Could not connect to <ip address>

Server Admin was unable to connect to the server at <~ip address>

Server Preferences tells me that this host cannot be found on the network too.

Point is however that both these apps run on the host with that very IP address. It is set up in System Preferences > Network, and is hardcoded, not given by the DHCP server in the router. I can also connect to the web server running on this host using the laptop and an ipad.

This is quite annoying, especially as Server Admin is the only app that lets you manage the host it runs.