Virtualized firewall

[steilfirn_8000]

Merry Christmas!

I have tried to migrate my small network from Sophos XG over to OPNsense but without luck.
My setup is/was:

- Virtualized OPNsense with direct internet conneciton + static IP
- Virtualized OPNsense with NAT
- Turris router (CZ modified OpenWRT)

As I have two remote sites I wanted them to connect via ZeroTier S2S VPN + OSPF routing and here my pain started.

From Turris I was able to ping the NATed OPNsense without any issues - worked flawless.
From my local OPNsense I had an average ICMP package loss of around 50  %.
Also OSPF routing was not working due to that.

Any idea what might be the root cause?