The IPSEC VPN connection of USG2100 and USG5100 will cut itself after connecting for a while, it needs long time to connect automatically
The state of VPN is normal after the IPSEC tunnel was built. But when the date is blocked
Up, IEK SA on USG2100 is normal, SA in the second phase was deleted, it doubt that the survival time is up.SA is deleted, The SA of USG2100 is not deleted and renegotiate, but USG2100 configure IKE DPD 10, it will reset SA and re-negotiation with the other side if it detects that the other SA no longer exists, but the problem is still not resolved
Change IKE DPD 10 into IKE DPD INTERVAL 10 2 parameters, then it is normal.
It will appear the phenomena that the connection of cut itself after the new version using autodial IPSEC and IKE DPD ON-DEMAND.