We've just installed 5 Ubuntu 8.04 servers into our datacentre. Four of them work fine, but the fifth stops responding to PING and OpenSSH (both through their puiblic IP's) after a few hours. However, if we Radmin to one of our Windows servers on the same local network as where the Ubuntu server is, we can ping and OpenSSH to it from their. The problem seems to just happen on the public interface, after a while. Rebooting it fixes the problem for a few hours.
Once the problem happens, another symptom manifests itself: the server itself can still ping the default gateway, but no further.
We've tried swapping different public IP's for this server, but the problem still happens to this server.
Another time when the server stopped responding, we pulled out the network cable and plugged it into an XP Laptop. The ping worked to the laptop and started working again on the server (for a while) once we plugged the cable back in to it.
We're really struggling with this problem and an y help would be appreciated.