Serial connection timeout after a while

Hi there,
recently I updated my Monoprice Maker Select v2 (Wanhao i3) with a Melzi board to the Marlin 2.0 Firmware.
At the same time, I set up a Raspberry Pi 4 4GB with Octoprint 1.5.2 to control the printer remotely.

Unfortunately, after about one hour of printing (50 min - 1:15h), the Serial connection times out, according to Octoprint because the Printer is no longer responding.

“No response from printer after 6 consecutive communication timeouts, considering it dead. Configure long running commands or increase communication timeout if that happens regularly on specific commands or long moves” states the log from Octoprint.

The error happens when printing from the server and when printing from the SD, started via the server.
In case of printing of the server, the print fails. With SD, the printer continues on its own.

The Printer is attached via a 1,2m USB cable, the Pi has the original USB-C Power supply.
I already tried to lower the Serial rate from 250000 to 115200, with no difference. do i have to go even lower?

Somewhere I read for another printer that you can change the priority of the serial ports of the board between the LCD and USB. Does anyone know if this is possible on this printer to?

I had to reduce the size of the firmware by removing some features to make it fit, is it possible, that the storage of the board is too full and some buffer overflows?
Do I have to configure Octoprint in a special way?

Attached my configuration.h, with informations pieced together from stuff I found online...

Let me know if you need more information.
Thanks in advance for the help!

Edited 2 time(s). Last edit at 01/13/2021 06:09AM by apfelsaftbaum.

Hi,

Comment in //#define SERIAL_PORT_2 -1

that's it normally!

Edited 1 time(s). Last edit at 01/25/2021 12:01PM by NeueKlasse.

@NeueKlasse

No

-1 is for USBCDC serial, ie USB D- and D+ pins go directly into the processor. No discrete usb serial chip.

The melzi board has a usb to serial chip

i only get Octoprint to Work with my MKS SGENL if i comment this line in.... otherwise it doesn't work for me.

MKS SGENL has USBCDC (32 bit, lpc176x based)

this post is about a a completely different controller the MELZI (8 bit atmel1284p based)