I have a very similar issue. I don't know exactly, when it started, but iPad is connected to Wifi and everything works fine. Only JRemote does not find the JRiver server.
I tried to downgrade to an older JRiver version, with no success.
I did a fresh install of JRemote, nop.
I reset the iPad, and restore from iCloud, no success.
I reset the iPad and only installed JRemote, no success.
Today I had same issue with my iPhone.
What always helps, disable and re enable the Wifi of the iPad. Then it works for a short amount of time.
But don't get me wrong, all other apps always work and Wifi is OK always.
To me it looks like, JRemote does not like the latest iOS version, to which reason ever.
My wife has not installed the update on her iPad, she has no issues so far.
At the moment it is annoying.
Any suggestion?