I have an issue with 2 servers (which are also a domain controllers). They are on differenet subnets connected by a hardware based VPN. We have eliminated Networking as an issue. Using packet sniffers (wireshark) on both sides all traffic appears to pass normally in both directions. Packets arrive and are acknowledged. Addtiionally, these 2 server can talk ANY other machines on either subnet without issue.
However, pinging from the Windows command line shows one traffic flowing in one direction only, ie it does NOT show the same results as wireshark. Domain replication only works in one direction, DNS updates one direction, etc.
Have tried removing and re-installed the NICs. Firewalls off on both sides. There are no name resolution issues on either side.
This one is driving me insane. If you need me to post anythig I am MORE than happy too.