Hi @SaferHarbors,
I’d recommend reading the first few comments in this thread to see a few strategies for limiting power usage by the flight controller, and making sure you have a sufficiently high capacity supply/regulator for the onboard computer to operate without disruptions.
What’s the current-capacity of the converter at each end, and have you considered voltage drop through the tether? This comment may be a useful summary for the parts to consider when determining topside powering requirements and efficiency. In particular, a single T200 thruster at 16 V can use up to 24 A at max throttle, so running 4 or 8 thrusters at once would need significant throttle limiting to avoid under-powering and shutting down the control electronics.
I’ve been using Monterey for several months without issues, so that shouldn’t be a problem 
Mine only does that if the tether is disconnected or something equivalent (e.g. the Fathom-X in the vehicle has insufficient power to communicate).