Strangest problem - unstable firewall
Recently, I'm having to deal with a very strange problem. At my workplace, we've changed our WAN link. Same IP, same ISP. However, after that change, many machines here are having trouble to communicate with the firewall. The internal network is answering to ping requests just fine.
In these machines, if the IP is changed, be it via DHCP to static IP, or via one static IP address to another, or any other way, it tends to work. The exact method varies by machine. The problem is that after some time these machines stop communicating with the firewall again, and we have to repeat this process. We can even put the machine to the IP address that was previously being used to make it work.
We also have 2 WAN links, and there is a rule that sets the default route, which was also changed when the new link was set up, since it was faster.
Anyone have any clue of what this could be?
The problem is that after some time these machines stop communicating with the firewall again
This could be 1000 different things. Need to do some basic connectivity troubleshooting and see exactly what is failing.
Here are some more characteristics rrom this problem. The WAN connectivity doesn't actually stop. What is actually stopping is the e-mail manager program, such as Thunderbird and Outlook, and only for certain machines. Thunderbird, for example, stops at the SMTP connectivity process. Whenever the e-mail managers aren't working, the firewall machine won't answer to ping requests. The Internet is always fine though.
Reconnecting the network cable fixes the problem (ping and e-mail managers) for some time, but then it comes back. Changing the IP does the same thing.