I have my setup like this. The Jot server is on one VPS with some other web apps and the client and my UNA installation on another.
I did spend a considerable amount of time trying to get my original shared host provider to open up the necessary firewall ports but eventually gave up and just went and got a small VPS.
To be honest, the set up on my own wasn’t terrible. There was a little trial and error getting the right ports opened but once I figured that out it was good and at the risk of causing a sysadmin curse on my entire environment, I can say it’s been solid as a rock since I got it configured.