Changes to hardware?

[acme2k]

I got it working with that guide as well on a X1 Carbon 8th gen.
But i had to use the DKMS build method posted by @ndane.
I have the same problem as others that after standby the modem is sometimes still present, sometimes not.

Another problem i'm facing is that with the kernel mod and serial changes in place, the usb connections (e.g. usb-c hub, usb-a ethernet adapter) get disconnected and reconnected from time to time, like every hour. The white LED next to the usb-c plug is flashing meanwhile.
Anyone else facing that kind of behaviour?

One thing i asked myself: are the changes made through the serial connection permanently flashed into the modem?
If so, what are the default values?
AT+GTUSBMODE is wrote down. It initially was 0.
But what was the default for AT+CFUN before the change?

I'm gratefull for any help or suggestions.

Regards, acme