Unable to reach other node with Wireguard and HA

[duimeziod]

I have 2 OPNSense routers/firewalls setup in high availability and they also serve as Wireguard VPN servers. I can reach my LAN externally with the sole exception of the other OPNSense. The one that is reachable is the one that is the CARP master, while the one that is the backup is unreachable. When the nodes witch roles, the reachability switches as well. How can I configure them so that both are reachable over Wiregard regardless of which is master?