Here is octoprint.log just before losing connection. Every time it disconnects like this, with a SerialException. This section in particular was during a print running from the SD card, so the motors were definitely moving when the server lost connection.
2021-01-31 23:30:38,857 - octoprint.util.comm - INFO - Changing monitoring state from "Offline" to "Opening serial connection"
2021-01-31 23:30:38,858 - octoprint.plugins.meatpack - INFO - [Serial]: Cannot query packing state -- port not open.
2021-01-31 23:30:38,858 - octoprint.plugins.meatpack - INFO - [Serial]: Cannot query packing state -- port not open.
2021-01-31 23:30:38,886 - octoprint.util.comm - INFO - Changing monitoring state from "Opening serial connection" to "Connecting"
2021-01-31 23:30:38,894 - octoprint.plugins.meatpack - INFO - [Serial]: Config var [Enabled] synchronized (=enabled).
2021-01-31 23:30:38,894 - octoprint.plugins.meatpack - INFO - [Serial]: Config var [NoSpaces] synchronized (=enabled).
2021-01-31 23:30:38,894 - octoprint.plugins.meatpack - INFO - [Serial]: MeatPack configuration successfully synchronized and confirmed between host/device.
2021-01-31 23:30:38,895 - octoprint.util.comm - INFO - M110 detected, setting current line number to 0
2021-01-31 23:30:38,997 - octoprint.util.comm - INFO - M110 detected, setting current line number to 0
2021-01-31 23:30:39,015 - octoprint.util.comm - INFO - Changing monitoring state from "Connecting" to "Operational"
2021-01-31 23:30:39,086 - octoprint.util.comm - INFO - M110 detected, setting current line number to 0
2021-01-31 23:30:39,254 - octoprint.util.comm - INFO - Printer reports firmware name "Marlin bugfix-2.0.x (Jan 31 2021"
2021-01-31 23:30:39,271 - octoprint.util.comm - INFO - Firmware states that it supports temperature autoreporting
2021-01-31 23:30:39,304 - octoprint.util.comm - INFO - Externally triggered heatup detected
2021-01-31 23:30:39,648 - octoprint.plugins.tracking - INFO - Sent tracking event printer_connected, payload: {'firmware_name': 'Marlin bugfix-2.0.x (Jan 31 2021', 'printer_port': '/dev/ttyUSB0', 'printer_baudrate': 115200}
2021-01-31 23:30:41,860 - octoprint.util.comm - INFO - Printer seems to support the busy protocol, will adjust timeouts and set busy interval accordingly
2021-01-31 23:30:41,864 - octoprint.util.comm - INFO - Telling the printer to set the busy interval to our "communicationBusy" timeout - 1s = 2s
2021-01-31 23:33:53,470 - octoprint.server.util.sockjs - INFO - Client connection closed: 192.168.1.54
2021-01-31 23:43:44,593 - octoprint.util.comm - ERROR - Unexpected error while reading from serial port
Traceback (most recent call last):
File "/home/octoprint/python_venvs/octoprint1/lib/python3.8/site-packages/octoprint/util/comm.py", line 3831, in _readline
ret = self._serial.readline()
File "/home/octoprint/python_venvs/octoprint1/lib/python3.8/site-packages/OctoPrint_MeatPack/packing_serial.py", line 182, in readline
read = super(PackingSerial, self).readline(**kwargs)
File "/home/octoprint/python_venvs/octoprint1/lib/python3.8/site-packages/serial/serialposix.py", line 595, in read
raise SerialException(
serial.serialutil.SerialException: device reports readiness to read but returned no data (device disconnected or multiple access on port?)
2021-01-31 23:43:44,595 - octoprint.util.comm - ERROR - Please see https://faq.octoprint.org/serialerror for possible reasons of this.
2021-01-31 23:43:44,602 - octoprint.util.comm - INFO - Changing monitoring state from "Operational" to "Offline (Error: SerialException: 'device reports readiness to read but returned no data (device disconnected or multiple access on port?)' @ comm.py:_readline:3831)"
2021-01-31 23:43:44,608 - octoprint.plugins.action_command_notification - INFO - Notifications cleared