Have a Win2008 server in a small LAN. It is running as a domain controller and is also running an email server. LAN is connected to Internet via a ZyWALL router (192.168.1.1), and it has worked well for a long time. Yesterday I noticed that the server seemed to not access the Internet anymore (mail server failed dns lookups to external dns). Inbound emails work fine (the server responds to external requests).
Investigation showed that the server doesn't "see" the router.
I'm able to ping the router from other devices in the LAN. From the server I'm able to ping all other addresses - except the router address. From PCs in the LAN I'm able to ping the server's IP address. This tells me that there may be something that prevent the server to access the router. Have checked the routing tables, and the address 0.0.0.0 is routed to the correct address (192.168.1.1).
Expect that there may be some process or service that prevents the server from accessing the rouer's IP addres, but I'm not able to fine what it is. The server is running Malwarebytes to prevent attacks and malware. Have tried to disable it, but not sure if I've done it right.
Are there any other steps to take in order to solve this problems? Thanks!