Default ports you need to have opened.
TCP 26900
UDP 26900-26903
I will note that even though port 26903 isn't listed as being used for anything, not having it open often prevents people from connecting. Never have figured out why this is.
8080-8081 are at your discretion. Usually keep them closed unless you manage the server remotely, or have a remote management tool that needs them.
I believe I was helping you in the Discord server the other day, but I got pulled away while assisting. I know both of us are pretty active on the official Discord. (At least the log in the OP looks very similar to one I was working with, and your situation sounds similar as well.)