I am using Octopi 1.37 on a MTW Create, linked via the IP address. When the print is about to stsrt (everything at temperature) the carriage moves for a few seconds and then stops with an "unhandled communication" error message. I have to shut off the printer, delete the print from the upload list and start over.
The interesting thing is that on the second try it works well. Thereafter I can print as much as I like without issues. If i switch off the printer down for a day and then come back I will get this same error message. This occurs consistently. As long as I do not shut the printer down everything runs smoothly. i am at a loss to explain why this is happening.
I've run into similar behavior on my Kossel after I replaced an SBASE board that shorted one of the stepper drivers with another one of exactly the same board. In my case, oftentimes when I start a print and it's heating everything up, the connection will drop as you're seeing. If I reconnect and restart it, it works fine. I've never had it drop once the head starts moving. I've also found that the communication drops happen much more often when the garage (where the printer is) is warm. It never happens when it's very cold.
I've not been able to root down a real reason, but I know it started when I swapped the control board after the short. USB can be pretty finicky. Make sure your USB cable is as short as reasonably possible and has ferrite choke(s). If you have the spares lying around, a different Pi or control board may be more tolerant to the EM noise that causes many "random" connection drops.
Probably not the "do this and it'll work every time" direction you're looking for, but I hope this helps your quest. Maybe someone smarter than me will jump in with the "every time" solution and we can both learn something. =)