NTVDM.EXE Hard Error after 1 Hour Idle between 2 Servers Behind an F5

We have 2 servers talking to each other behind an F5 which is behind a firewall. That connection times out after an hour of idle. I can start a remote desktop session to one of them and then map a drive to the other server or start a SQL*Plus session and I’ll get a NTVDM.exe hard error after an hour even though the remote desktop session is intact.

I created a forwarding profile from the fastL4 with an 8 hour idle timeout and applied it to each server. Looking at the firewall logs (which also have an 8 hour idle timeout set), there is no communication between me and the server after the initial remote desktop connection and there is never any communication between me and the other server.

So how is the F5 timing out the connection between the 2 servers? This connection never times out if the servers are not behind the F5.