openHAB does not use port 9001. Some users of openHANian have installed Frontail that uses port 9001.
Your title says upgrading from OH2 to 3 but your post says 3.0.2 to 3.1.0 Which is it??
Are you using openHABian?
How to ask a good question / Help Us Help You - Tutorials & Examples - openHAB Community