Server1 is on our domain, located at Site A and functions as a file server. All clients at Site A can access the server without issue.
Site B is connected to Site A via IPSEC VPN tunnel. All clients at Site B can ping Server1 by name and IP. They cannot access its shares though. A 'net view server1', 'net view ipofserver1' and 'net view server1.domain.local' from a client at Site B results in "System error 53 has occurred. The network path was not found."
Clients at Site B can access shares on other servers housed at Site A.
No firewall is running on Server1. Most recent Windows Updates were installed 5 days ago, and this problem just started up this morning, so I don't suspect an Update caused this.