So I just switched my server from osx to windows.
When connecting the server to the outside, pms connects briefly (green) then turns red after a second saying it is not accessible from the outside.
Yet, the server is accessible from an external dynamic dns ip, port forwarding is working etc.
This behavior keeps on appearing without solution ever from the team over the posts and years.
not sure if this helps, but i had this issue pop up a few months ago. i have comcast internet and they added a security feature to the modem\router which caused this issue for me. i turned it off and haven’t had the issue since.