Hey all, this has been happening to me for months and it's getting worse. I have Ubuntu 9.04 server edition set up on a dedicated machine at home to act as my router/firewall to the Internet. It's set up with two NICs with one going to our cable modem and the other to a LAN switch, and I have Shorewall masquerading for it all. And so you know, it is a minimal headless console setup.
As of late, it seems that almost every Friday morning the system stops transmitting to/from the Internet. I can connect locally to the machine, but the system appears as if it is working properly. I can ping the Internet, but can't connect to websites from the server or from any local computer. I'm at work when it happens and when I come home I find it's been like this since mid-morning. I reboot the machine and everything goes back to normal except my dynamic IP addresses change.
I have no idea where to start looking into this problem. I'm usually pretty good with hacking around Linux, but this seemingly errorless connectivity issue has me baffled. I don't have any sort of cron jobs running Friday morning that would do this either. I hate to say my option appears to be reinstalling from scratch, but I just reinstalled this year and with fresh hardware. Any ideas? Need more information?