My home network is completely broken because my cable modem refuses to work if there's any address sharing whatsoever.
It doesn't matter if it's my main router, a spare router, or even my laptop creating a hotspot simply for my phone.
Even when my laptop itself is directly plugged into the router, it's a bit wonky (but mostly works).
Too bad the cable modem is in a horrible place in the apartment.
I've never seen network components act so oddly.
My guess is that the cable modem is mostly dead and any more than a few random connections makes it completely give up.
So it's not necessarily sharing the network, but the result of so many devices reaching out to the Internet at once.
This would explain why the routers sometimes seem to work for a bit, too. Until nothing does a few minutes later.
Cable company didn't even ask us to power cycle the modem. They just shipped us a new one. 🤯