I reset /etc/ppp/options to the original values. I tried connecting three times, the second time with "disconnect/connect", the third time with unplugging/replugging the USB stick. I confirm that connection works reliably now.
I enabled NM_SERIAL_DEBUG for this test, log attached. I still get a couple of "CREG: 0,2" messages (two per second), I don't know whether that's intended, but it's not millions any more, and connecting works fine.
I reset /etc/ppp/options to the original values. I tried connecting three times, the second time with "disconnect/ connect" , the third time with unplugging/ replugging the USB stick. I confirm that connection works reliably now.
I enabled NM_SERIAL_DEBUG for this test, log attached. I still get a couple of "CREG: 0,2" messages (two per second), I don't know whether that's intended, but it's not millions any more, and connecting works fine.
So from my POV this is fixed.