I treat the ISP-provided gateway as a part of the internet, I don't use its WiFi and don't attach other devices to it which are not my own router or a honeypot.

I treat the ISP-provided gateway as a part of the internet, I don't use its WiFi and don't attach other devices to it which are not my own router or a honeypot. The subnet the gateway resides in is like a moat surrounding a castle.