Greetings,
I am having an issue with a server running 2008 R2 with Exchange, its dropping connections to and from the WAN at random times. The connection only drops to external resources, so I can still ping to and from other devices on the LAN including the default gateway (DG). Other servers using the same DG are not having any issues. All of this started after we switched to a different router, we are now running a Ubiquiti Edge Router Lite, I am fairly confident in its configuration, as no other servers using it are having issues, but I cannot rule it out as the cause. We have three servers running 1 to 1 NAT through the router, two of the servers are having no issues, and the configuration for all servers is pretty much identical. While changing routers we also move the server from a different physical location and added some RAM to it.
When the Exchange server is working correctly I can ping everything as I should, however, when the connection drops to the WAN some perplexing things happen:
When I ping to 8.8.8.8 or any external address the TTL value will change substantially from 64 to 255 (Ubiquiti routers respond to pings with a TTL of 64, but Cisco gives a TTL of 255).
If I do a trace route when everything works the first hop is the correct gateway (GW) but when it stops the first hop switches to a different Cisco GW that we have.
When the GW swaps we obviously lose our NAT translation making the server inaccessible externally.
Steps I have taken:
Swapped patch cables
Different switch ports
Different NIC (including onboard to a separate card)
Configured switch port and NIC to be 1GB full duplex instead of Auto negotiate
Restarted the server
Checked gateway settings, static routes and the hosts file, there is no reference to the second Cisco GW
Windows firewall is disabled on the server
I have just about have ran out of ideas on this one, I am thinking it may be related to proxy ARP? I do not have control over the Cisco router so I will be contacting our service provider to see if it is enabled. Any thoughts would be appreciated.
Thanks,
Joshua Schrader
