Never use the ISP provided equipment on your network. Even if you must use their modem and router, have them turn of the wifi, and connect your router to their garbage using the WAN port to connect from their LAN port with nothing else connected. If they refuse to turn off their wifi and you can't do so through the admin, cover their crap in a Faraday cage to kill the signal. Always enter your own DNS settings on your router, never use their DNS. Make sure to use an encrypted DNS to avoid them hijacking it.