IPSec traversal through untangle in bridge mode issues

Hi,

I have the following network, with untangle (Lite) in bridge mode:

The IPSec tunnel is established and for the most part appears to work fine. However staff noticed that when accessing the WebServer via the IPSec tunnel after I inserted the Untangle that ajax requests would stop working. I tracked this down in the logs, and the TCP connections were being established, but would then stall.

And then the next day we noticed that we could no longer deploy are CMS (alfresco) via the tunnel. The connections would just stall for no reason. In addition I had an scp that just stalled for no reason.

The first thing I thought of was that the Untangle Attack Blocker was throttling the IPSec as it traversed when large requests were going through, but disabling the Attack Blocker didn't help. The firewall hasn't got any rules enabled, and nothing else made sense.

I disconnected the untangle, and suddenly everything was working fine again.

The last time I saw issues like this it was related to MTU. However I can't think why Untangle would be affecting the MTU in any manner.

Has anyone else had any similar issues?

Cheers, Ed.