Connection to Homebridge not working

Hi everyone,
I am running Homebridge in a docker container on an Ubuntu VM on proxmox. The installation is fine and I can also connect to the UI via port 8581. Unfortunately, when I try to add the bridge to Homekit, it "times out". The VM is on VLAN 3 and the Homekit hub is in VLAN 10. I opened the firewall to "accept" between those 2 VLANS.

What else could be the problem?

According to TCPing the port that is used is open.

Open for any tips - I have run out of ideas