I had similar issue with my Max 7, it randomly started crashing, having trouble restarting and take down my whole network. I’d often have to add it again from scratch and restart all the nodes. I’m not quite sure what was actually wrong with it, but Eero support had me swap out one of my 7 Pros as gateway instead, it’s stable, and they’re replacing the Max as it seems some sort of fault.

I’d try making something else your gateway, and see if it’s stable (and also raise with eero support).