We have been experiencing an unstable VPN connection at one of our sites. VPN tunnels randomly go down. Looking at the log in the web portal shows "Peer closed connection" and "The peer is no longer responding" between the gateways. We can also see logs like "Informational Exchange Received Delete IPSEC-SA from Peer" coming from the remote gateway. Following is an example of one of the events:
Looking at ike.elg log file indicates towards lots of INVALID-COOKIE before and after phase 1 and phase 2 ike negotiation.
Troubleshooting steps taken:
1. Cross-checked VPN site settings on both ends
2. Delete and recreate VPN sites on both ends
3. Increased WAN bandwidth from ISP
SMB gateway: 1450 Appliance | Version: R77.20.75 (990172321)