192.168.1.1 and 192.168.0.1 are popular private gateway addresses, not universal router addresses. If one does not open, that does not mean the router is broken.
The router may use a different factory address
Manufacturers and ISPs use many local ranges, including 10.x.x.x and other 192.168.x.x networks. Mesh systems and mobile hotspots often choose different defaults from traditional routers.
The address may have been changed
An installer, previous owner, ISP, or network administrator can change the LAN subnet. Your connected device will normally learn the current gateway automatically through DHCP, so checking the gateway is more reliable than guessing.
You may be connected to a different router
Homes with an ISP gateway plus a second router, mesh system, extender, or access point can contain several networking devices. The default gateway shown by your device points to the router currently handling its traffic.
Guest networks can block administration
Guest Wi-Fi is often isolated from local devices, including the router management interface. Join the main network or use Ethernet.
Use the correct local address
Follow How to Find Your Router IP, then type that address directly into the browser address bar.