What is the problem?
When connecting to my Anet running Marlin 1.1.9, I have always left the port set to AUTO. I have never had any issues. Now, with 1.4.0, I can see it trying to connect, as it reboots the controller board as always, but on the terminal, it shows:
Changing monitoring state from "Offline" to "Detecting serial port"
Serial port list: ['/dev/ttyUSB0', u'/dev/ttyS0']
Could not connect to or enter programming mode on /dev/ttyUSB0, might not be a printer or just not allow programming mode
Could not connect to or enter programming mode on /dev/ttyS0, might not be a printer or just not allow programming mode
Changing monitoring state from "Detecting serial port" to "Error: Failed to autodetect serial port, please set it manually."
Failed to autodetect serial port, please set it manually.
If I set it to /dev/ttyUSB0, it connects without issue
What did you already try to solve it?
I have lengthened timeouts in the connection section, checked wait for start on command" all to no avail.
Additional information about your setup (OctoPrint version, OctoPi version, printer, firmware, browser, operating system, ... as much data as possible)
Octoprint 1.4.0 on Octopi0.17.0, Raspberry Pi 4B 4G version, Anet A8 printer, Marlin 1.1.9 firmware