Sending ArtNet using Localhost stopped working in macOS 26

[lightupyourmind]

I used artnet using the Localhost for sending DMX between two softwares, running on the same machine (QLC+ and Arena). It worked like a charm until I updated my Mac to macOS 26. I guess the update is the problem, I did not changed anything else. Arena shows the error: sendmsg failed: no route to host
in QLC+ there is the ArtneNode of my Arena instance visible for a short period of time after activating it in Arena, but it can't recieve any dmx data and disappears after some minutes.
Any suggestions how to solve this problem? I got a gig on friday and am starting to worry a bit...

All the best!