We have a S2S IPSEC tunnel betweend 2 digi WR21. The tunnel will establish and pass traffic and every now and again the tunnel drops and we get these errors in the logs.
A reboot of either side brings the tunnel back. Run a Diff on the config to make sure we're identical on both sides and it is.
10:31:18, 08 Jul 2020,IKE Request Received From Eroute 0
10:31:18, 08 Jul 2020,(1177) IKE SA Removed. Peer: ,Negotiation Failure
10:31:18, 08 Jul 2020,(1177) IKE Negotiation Failed. Peer: ,Retries Exceeded