OctoPrint will not connect to my Prusa i3 MK3S anymore

**What is the problem?**This was all workinng well for several months then yesterday when attempting to load directly from PrusaSlicer to the OctoPrint server I got no response. At octoprint.local I could see that the printer was not connected and I kept timing out when trying to connect. The terminal screen showed
Send: N0 M110 N0*125
Recv: Command not found!

What did you already try to solve it?
I don't really know how to do much. When I reboot the Rpi the Prusa reboots so there is some connectivity. Booting in SAFE mode did not help.
On my browser at octopi.local I can see the webcam feed but not printer specific info like temperature and the status of the printer is DISCONNECTED

Logs (syslog, dmesg, ... no logs, no support)

I can't figure out how to get the serial.log from the Rpi but it is the same as the following screen grab from my browser:

Changing monitoring state from "Offline" to "Opening serial connection"
Connecting to port /dev/ttyACM0, baudrate 19200
Changing monitoring state from "Opening serial connection" to "Connecting"
Connected to: Serial<id=0xaf0b1e50, open=True>(port='/dev/ttyACM0', baudrate=19200, bytesize=8, parity='N', stopbits=1, timeout=10.0, xonxoff=False, rtscts=False, dsrdtr=False), starting monitor
Send: N0 M110 N0125
Recv: Command not found!
No answer from the printer within the connection timeout, trying another hello
Send: N0 M110 N0
There was a timeout while trying to connect to the printer
Changing monitoring state from "Connecting" to "Offline"
Connection closed, closing down monitor

Here is a log fileoctoprint(1).log (3.2 MB)

Additional information about your network (Hardware you are trying to connect to, hardware you are trying to connect from, router, access point, used operating systems, ...
I am using:
Rpi 4B
OctoPrint 1.4.2
Connecting with a USB cabale
Any help greatly appreciated