Before learning about how to disable router bridge mode, lets quickly understand few things about it. The devices responsible for connecting to the internet and the Wi-Fi network at your home are:
A modem is mainly responsible for establishing a connection between your home and the Internet Service Provider’s network. Whereas the router is mainly responsible for connecting your wireless and wired devices to the modem. Each of them is designed to perform separate operations.
If you want to extend the range of your wireless network, then you can use extenders. But many routers have the Bridge mode that allows the routers to function as an extender, repeater, or access point. Make use of the instructions on this site to disable the router bridge mode.