Activating Wireguard drops the network connection

I can not track this down and dmesg does not show anything useful to me.
I have CoreELEC (21.0-Omega Amlogic-ng.arm gxl_p212_2g) on a S905x box running fine so far. But I wanted to add Wireguard, so I created the necessary config, which shows up in the Network management section. As soon as I tryo to enable the connection, my wireless connection drops and only comes back when I reboot the device.
I also tried with an Ethernet connection, but this one drops too as soon as I try to establish a Wireguard tunnel. For the Ethernet though, I can unplug and replug the Ethernet cable for the connection to come back up again.

The last test I did was by using connman manually via ssh. It sees the services fine and as soon as I do a connect , my network connection gets dropped again.

Are there logs that could show me what is happening in my case? I am a bit lost at the moment.

I did just another test with the wq-quick method from entware and it is the same behavior. I wonder if I can do something fundamentally wrong to get this outcome or if this is a bug somewhere?