I found out that ISP provided crap can do one thing OK. I have an ISP provided cable modem / router / wifi doing only the cable modem part and bridging the connection to a MikroTik router. Then I have another ISP provided router / wifi only doing the wifi part, again bridged to the MikroTik.
Both the ISP provided boxes were crashing pretty consistently when they were doing routing, firewall, wifi etc. (torrenting with a VPN while watching a 4K stream over wifi would just melt the box) but when they’re only doing one thing they’ve been working fine.