Joking, about the LAN suggestion (although the method does work, it was there from Novell Netware days), but not trolling about the JNLP suggestion. I genuinely thought it would work.
I stopped using Java probably a bit before JNLP came out, so never checked it out.
What sucked about JNLP? I can google, but what was your experience with it?
Not GP, but:
Oh, JRE too old? Link to download the latest? Now it accepts the JRE, but the JRE refuses it with security errors. So you turn those checks off and the jnlp runs but crashes with an obscure error. So you try another JRE until you find a version that works.
While doing this, you interact with Oracle, at all times with the fear of their lawyers, until you decide to use a foss runtime. Now you are managing runtimes from different vendors with different configs and locations.
Write once, troubleshoot everywhere.