Hello,
First, let me just say that I am not a tech, and you probably have no business listening to anything I say.
I used to have a problem like that with mine. It came up temporarily while I had assigned the machine a public IP for troubleshooting. Seems to be a problem with the drivers Linux is using for the ethernet card. I was never able to conjure up a proper solution as the problem somehow went away once the machine was back on our side of the firewall. I was however able to get the web interface working again when it went down without rebooting the whole machine by doing the following:
Log on to the machine as root
Get into a shell
ifconfig eth0 down
ifconfig eth0 up
basically this reboots just the ethernet card. If your problem is the same as mine the web interface should start working again.... at least temporarily.
Hope this provides some clue
