@Arrowstar, first I just wanted to thank you for a great tool and all the time you've put into it.
I think I've run into some kind of bug in v1.5.8 which is preventing operation of the TOTConnect in order to get real-time data from my local machine (same one that runs the game). I originally ran into the error on KSP v1.2.2 (with RSS and Realism Overhaul plus a bunch of other mods) but I've re-tested on KSP v.1.3.0 (with a few mods, but nothing huge).
I can open the MCC Real Time System UI and when I click on "Test Connect to Remote Host", I get an accurate list of vessel (which leads me to believe the plugin is correctly loaded); however, when i select a vessel and click, "Connect to Real Time System", I hear a windows error chime in the background and nothing connects.
A dive into the KSP.log shows some KSPTOT Connect errors such as, "". I've links the full logs from both v1.3.0 and v1.2.2 in case it helps. I went back to KSP TOT v1.5.7 and it seems to connect OK even using the KSP TOT Connect plugin from 1.5.8 (suggesting perhaps a change to the main program and not the plugin is causing the issue).