Tunnel established but no traffic passes

Introduction:

The purpose of this article is to aid in troubleshooting network connectivity via IPSEC VPN. In this scenario the site to site VPN between two VyOS and the tunnel status is up however, both local and remote subnets are not able to reach each other or only one way communication is working

Solution:

1. Verify the IPSec configuration. Check if the local and remote network are configured correctly (phase 2 selectors).
2. Verify that the firewall rules are created to pass VPN traffic( rules to pass from LAN to VPN and VPN to LAN). Check if the ESP ports - 500,4500 are open.
3. Check routing, if there is any conflicting static routes or an active route is present to the remote subnets for a route based vpn.
4. Take packet capture to check if the packets are flowing through the tunnel.

If the above options do not help you, please raise a technical assistance ticket and attach the configuration and logs of the device.