https://www.cisco.com/c/en/us/td/docs/security/asa/asa96/configuration/vpn/asa-96-vpn-config/vpn-anyconnect.html Configure Dead Peer Detection Dead Peer Detection (DPD) ensures that the ASA (gateway) or the client can quickly detect a condition where the peer is not responding, and the connection has failed. To enable dead peer detection (DPD) and set the frequency with which either the AnyConnect client or the ASA gateway performs DPD, do the following: Before you begin This feature applies to connectivity between the ASA gateway and the AnyConnect SSL VPN Client only. It does not work with IPsec since DPD is based on the standards implementation that does not allow padding, and CLientless SSL VPN is not supported. If you enable DTLS, enable Dead Peer Detection (DPD) also. DPD enables a failed DTLS connection to fallback to TLS. Otherwise, the connection terminates.