I've been using the G6 for just over 18 months and mostly it has been really well behaved. That said, this last month (over two sensors) I've had more sensor errors than usual - but typically restore within 30-60 mins. Calibrations using a OneTouch Ultra are usually very close.
Have been using the G6 since 2018 and rarely get an error, I use the backs of my arms which have worked fine - are you just getting random sensor errors where it’s unable to connect ? Have you called Dexcom ?