No clues from the logs - but picking up on some previous comments. It appears in my scenario that DPD is not working is terms of forcing a disconnect when the link is dead/inactive.
The 2.0.2 box shows the in vpn as inactive and the logs are full of no response/timeout errors - the the 2.1 beta is sitting there saying the link is active and that the last activity was some hours ago! DPD is set to 10 secs and 5 retries at both ends.
If the 2.0.2 box is restarted it tries hard to make the link - but is completely ignored by the 2.1 beta - as the link is till active?? Do the reverse and force the 2.1 box to restart and the 2.0.2 box detects the missing peer and initiates a new link perfectly.
SO DPD broken in 2.1?
Andrew