We have a site to site client that is having issue with intermittent disconnects. The Main endpoint is a CIsco ASA 5520 8.4.3 and the remote site has a a Cisco ASA 5505 8.2.5.
If we have a disconnect, we can "logout" of the Main ASA and the connection seems to find itself and traffic will flow. This take place about every 1 - 5 minutes but if you reset the crypto (which I am assuming you do) by logging out under the Logging Monitor Session - ikev1 sessions. It all starts right back up.
I am stumped. At first I thought MTUs but I am not sure that is the answer.