Using version 4.3.1. We just changed internet providers to Comcast and installed Cisco ASA 5510s at each branch to create site-to-site VPN tunnels in hub and spoke to admin building where Unix server is located. Everything seems to work fine except Deja Win timing out sessions due to inactivity. Front desks are running Thoroughbred software and were having the same issue and we set keepalive timers to 45 seconds and seems to have resolved the problem however, still testing as the users are more active than the ones using Deja Win so we aren't certain that the problem is solved with that yet. Not sure if keepalive can be adjusted with Deja Win. Can this be adjusted and does this seem like we're looking in the right place for solution?
There is no keepalive setting in 4.3.1 (16 bit ICE.TCP).
There was one added to the 32 bit versions (ICE.TCP.PLUS and ICE.TCP.PRO) some years ago.
It IS likely that you are seeing the problem because either the Cisco (most likely) or the ISP is timing out the connection. More likely the Cisco because NAT tables always have to have inactivity timeouts. You MAY be able to adjust that on the Cisco (you'll need to check the docs). The timeout would have to be longer that the longest period of inactivity your users would have.
If it's the ISP, you've got no control.
Either way, if you were running PLUS you could send keepalives from Dejawin to prevent the NAT from timing the connection out.