A vEdge router logs 'DCONFAIL (DTLS connection failure)'. What is the most likely cause?

The most likely cause of a 'DCONFAIL (DTLS connection failure)' error on a vEdge router is a connectivity issue. DTLS (Datagram Transport Layer Security) is used to secure the control plane connections between SD-WAN devices. If there's a problem with network reachability, firewalls blocking necessary ports (e.g., UDP 12346), or routing issues preventing the vEdge from reaching the vSmart controller or other vEdge routers, the DTLS handshake will fail, leading to this error. While a certificate mismatch or organization mismatch would also prevent successful control plane establishment, they typically result in more specific error messages related to certificate validation or organization name verification, not a generic "connection failure." A memory issue is unlikely to manifest directly as a DTLS connection failure; it would more likely cause system instability or other process crashes.