Why does my Nebula-to-NonNebula VPN tunnel disconnect frequently?

Zyxel_Irene

I configure Nebula-to-NonNebula VPN with the correct configuration, but there is disconnected frequently, and there is not complete VPN connection shown on Nebula Control Center (NCC).

• Topology 

• You may see the incomplete VPN connection info shown on NCC

1. The disconnected status
2. Short tunnel uptime
3. No Last heartbeat

• How to solve this situation?

In the current design, users need to input a reachable IP address in the Private subnet field on NCC. It means You have to input an IP address is existed in the peer side, you can enter the interface IP 192.168.2.1 or PC2 IP 192.168.2.33 in the Private subnet field on NCC as the screenshot below. This IP will be used for ping check by NSG. 

• Reference

1. How to establish Site to Site IPSec VPN between Nebula and Non-Nebula devices
2. VPN Connectivity Check