No website accessibility from a VPN private network

Hi

I have a VPN wirequard with my brother over IPv6 and he wants me to be able to access his Home Assistant from me. The FW rules on the OpnSense look good, I can access web servers on his network. Unfortunately not to the IP and port of the Home Assistant.

His Home Assistant runs on a Raspberry Pi and is connected via LAN. Is there an IP filter in the default OS / Hass or other area on the Raspberry?

LAN 10.20.10.0/24 Location A and VPN network 10.11.10.0/24 Home Assistant 10.20.10.60:8123 Configuration.yaml http with trusted proxies also extended auwf the network 10.11.10.0/24.

routing or filter issue…
no fw on HAOS, …

ping and traceroute A ↔ B is your friend