I have been using octoprint installed on a Pi 3B+ for the last 6 months connected to my Creality CR-10. What I find is that after I switch on the printer, I manually select PRE-HEAT PLA to warm up the nozzle and bed, then go to my laptop in another room and open octoprint on a browser. I then connect to the printer, and can see the heating process. After a random amount of time, prior to both the bed and nozzle getting to required temperatures, octoprint will lose connection. I then hit the Connect button and try again - this time as the default settings are off, both nozzle and bed are going down in temperature, so via the windows I manually set them to the required temps. Again octoprint may lose connection, so I need to repeat the process, and may need to do it several times. ONCE the bed and nozzle get to the required temps, I have no further problems, including during the printing process. I have found that if I heat the bed first, then set the temp for the nozzle in octoprints window, then I have a better success rate. Note I have no problem manually setting nozzle and bed temps at the printer, only via octoprint. I wonder if anyone else has seen a similar problem?
Hotend and bed heat-up events come in two varieties: blocking and non-blocking. If the LCD-related commands to heatup your printer are the blocking variety (probably), then it will be unresponsive to OctoPrint while that's happening.
You might want to change your routine:
- start the printer
- start OctoPrint
- from OctoPrint, preheat
Many thanks - this method works for me, every time.