Hey guys,
I know these settings in Guidbedit might not always be relevent, specially in newer versions, but I did come across few scenarios lately, in R81.20 as a matter of fact, where we had to go to guidbedit and set below values to false to get VPN tunnel to work:
ike_enable_supernet
ike_p2_enable_supernet_from_R80.20
ike_use_largest_possible_subnets
I sometimes also check this on the gateway, though this was only problem few times, so probably not a requirement, but also something to consider:
gateway object -> other -> connection persistence -> I always check keep all connections
Andy