Been using jit.si for months with extended family (up to ~7 connections), not broken yet.

Same, approximately. I got one literal grandma to use Jitsi, and all of my literal grandparents to use BigBlueButton, and the latter actually took effort. Jitsi is significantly easier to use than Zoom et al., requiring no account or anything but a browser even to host a meeting, and having an extremely intuitive UI compared to eg. Zoom, with eg. the "Raise Hand" button being a hand icon right on the bottom bar next to mute, etc. where there’s just empty space in Zoom, instead of buried under a "Participants" button. BigBlueButton is slightly less simple (eg. you need to log in to host, at least by clicking “Login with Google” or with Twitter or Microsoft) but both have worked flawlessly over dozens of meetings and been understandable to my grandparents.

Then you are lucky. It breaks frequently (but randomly) and when it does, it's almost impossible to debug unless you have access to the broken machine (and that is unlikely given that you're probably at home and so are they).

Breaks how? I've used it on about 6 devices personally, roughly a couple of times a week and all our extended family have used it on one or two devices - Win10, iPad (I gather), Android, and Linux.

If it breaks a lot we must have been exceptionally lucky for none of us to have problems.

"It works on my machine" was generally the feedback I got from the server maintainers as well. It's true that only a few people had problems, but those people were the kind of people that needed to be listened to when they said "Jitsi doesn't work so we need something else". The problems in Jitsi were impenetrable for me and anyone else that looked into them, so saying no wasn't an option.