It doesn’t matter which OS you use. You need to contact your hosting and ask to disable firewall. Also you can check if you have security plugins. They can also block remote connections 

Hi, im with windows 11 now, previosly was with windows 10. When installing windows 11 i read will be security issues with not compatible procesor and motherboard, could this be the reason i cant register? 

it is about REHUB theme.

If there is a way to overcome this problem without going back to Windows 10, I would be grateful.

And i also on some free hosting plan with https://cp1.zettahost.bg/