I currently don't really have a way to test local; I can TRY to set that up, but it's iffy.
I think we'd at least be on the right track if I could reproduce the "host is not accepting join command" error, but I haven't been able to do this.
Perhaps this might help: when configuring the router, do I set the protocol to TCP, UDP, or TCP/UDP? Also, do I set it up as ppp0 or ppp1?
Currently, I tried setting up one service as TCP and one service as UDP, so I have 2 services named Dim3, selecting ppp0 or ppp1 didn't make any difference, as neither one worked.