I am having seemingly random disconnects of active RDP sessions (I am actively typing or otherwise interacting with the desktop) when connected over the VPN connection. The attempted to reconnect 1/20 pops up and proceeds all the way through 20 then drops. Once the session drops I can open a new session and connect again.

This started happening about a week ago,

The VPN connection is an IPSec VPN connection from a SonicWall NSA 2400. The NIC drivers are up to date. The VPN client is up to date. The firmware on the SonicWall is up to date (both regular and the early-release versions work the same).

I have attempted to connect over three ISPs all with the same behavior. Two different workstations were used to test the VPN connection.

The same behavior occurs when connecting to a domain workstation or server.

If I am within the firewall I can connect to the same workstations and servers with the disconnect.

The VPN connection has "enable fragmented packet handling" and "ignore DF (don't fragment) bit" set.

Is there something I am missing in where I am looking for the problem?