Before I begin, please don't rip me apart for the current configuration. I didn't do it ... I'm just trying to fix without taking it down to redo. :)
I have 2 3560 cats connected via a wireless link. One of the cats is connected to a cisco 3825 router which in turn is connected to the internet. Both cats have one Vlan (vlan1) with an ip of (switch1) 192.168.92.2 255.255.255.192 and (switch2) 192.168.92.4 255.255.255.192 and have a default-gateway of 192.168.92.1 255.255.255.192. On the router, its configured on Gi0/1.1 for a primary of 192.168.92.1/26 and secondary addresses of 192.168.93.1/24, 192.168.94.1/24, 192.168.160.1/24, 192.168.161.1/24, 192.168.162.1/24, 192.168.163.1/24 and 10.50.0.1/16 and 10.40.0.1/16. Its a mess but a work in progress to fix without taking everyone down.
On switch2, I have a linux box. When it has an ip address of, say, 192.168.92.43 (correct netmask and router of 192.168.42.1) ... it works and is accessible. If I change the ip and other network information (router 192.168.93.1) to be 192.168.93.2 or anything outside of the 192.168.92.1/26 subnet it is accessible for about 30 seconds after I bring the interface up but then goes away. It works fine on switch1.
What might be the culprit? I'm happy to provide sanitized switch and router configs.