This has something to do with some network setting. I tried same setup on my test server and it works fine with all the recent hassio_supervisor changes, so it's not it's fault as i have thought before.
Using IP address like: 192.168.0.7:7800 doesnt work, it returns code 1006.
Using unraid domain name works: somerandomgeneratedtext.unraid.net:7800 works and returns the web ui fine.
It's all weird for me.