Primary node is blocking access to second node

[b1nb4sh]

Hello,

I have bought an used apu4 board and installed opnsense on it.
Now I have 2 Nodes and added them to an HA.

I have added an interface lan_adm and allowed tcp:22 to from this network to any other network. Synched the two nodes and now comes the funny part.
I can connect to the second node with my admin pc, but after some time the connection get blocked...
So for ssh I get broken pipe and for the https connection I get sometimes a timeout. I have added some screenshots to show this situation
10.0.8.11 is my admin pc
10.0.1.3 is the second node