How Do I Quickly Restore an Interrupted IPsec VPN Connection?

Trigger IPsec negotiation by private network data flows. For example, two private networks at both ends of the VPN connection ping each other. If traffic can be properly triggered, deploy a continuous ping script. For details, see How Can I Prevent VPN Disconnections?.
If the negotiation cannot be triggered, check the Internet connectivity by pinging the VPN gateway IP address and the remote gateway IP address. By default, a VPN gateway responds to ICMP packets.
If connectivity is normal, check whether link switching occurs between outbound interfaces. That is, check whether the traffic for access to the VPN gateway is forwarded out from a non-negotiated interface.
If there are no multiple ports or the port path is normal, change the PSKs at both ends of the tunnel to trigger negotiation again.
If the negotiation fails, check whether the negotiation policies configured at both ends are consistent and whether the interesting traffic at both ends is mutually mirrored.
If the negotiation policies and interesting traffic configurations are correct, disable the VPN connection on the on-premises device. After the VPN connection state changes to Not connected, enable the VPN connection on the on-premises device and trigger a data flow.
If the negotiation still cannot be triggered, perform the following operations:
1. Record the negotiation policies, PSK, local subnets, remote gateway, and remote subnets of the VPN connection.
2. Use the existing VPN gateway to create another VPN connection. The negotiation policy, PSK, and local subnets are the same as those of the original VPN connection. Randomly configure the remote gateway and remote subnets.
3. After the new VPN connection is created, delete the original VPN connection and change the remote gateway and remote subnets of the new VPN connection to the recorded information.
4. Trigger the negotiation again.