Ok so i might have narrowed it down.
I installed a small server program and run it on port 81
changed bi port to 88
i could access the server page ok on 81 and ui3 on pc plus bi app, the moment bi stopped i tried refreshing the new server page and that wont load and times out, waiting for server page and ui3 to load and after 2 minutes they both became available again.
Looks like this could be a non bi problem and just a symptom of another problem.
ill try changing router next, oh this has been fun haha