okaay so after 4.7.0 was discovered to be unstable, i've gone backwards to 4.0 mainline and that's working perfectly (well, i say perfectly: USB-ETH ASIX88772 sends out zero data and/or can't *receive* data) - no crashes after 10 minutes.
soo... eeenterestiiing... next one to try: 4.4
l.
--- crowd-funded eco-conscious hardware: https://www.crowdsupply.com/eoma68