I had problems originally connecting to and keeping connection in gSender on my laptop.
It was running Win10 which would not connect/stay connected. Wiped it and installed linux and had the same problem.
After viewing com port logs I saw a ‘possible EMI issue’ warning after disconnects. Swapped out the USB cable that came with the machine for a shielded Belkin cable and have not had one single issue with connection since.
If anyone does have this type of connection issue (Com port connected but machine disconnected) try a shielded cable.