First of all apps/addons will not be geo locked if you use a vpn, it hides your true location by using servers in different countries, it won't help with buffering as speeds can be lower using one. That is down to the server that the addon is trying to access, BUT i don't know if you can use one with a box, you can use one with a PC and run 'kodi', not sure about a box.
Just a suggestion but try Tunnel Bear https://www.tunnelbear.com/
I use it on 3 devices icluding Ipad, it's subscription based but very reasonable and easy to use
ckeck it out on the playstore.