I can’t get online with my new router

QSince I changed ISP, everything except my iMac has been able to use my new router. The iMac says it’s connected to Wi-Fi, but only works over Ethernet. My ISP blames the Mac. Is it right? The most likely cause is your iMac trying to use an IP address on a different subnet from your new router. Open System Preferences’ Network

Apane, select Wi-Fi on the left and then check the first three numbers in the address shown on the right match your router’s IP address.

If not, you may need to click the padlock (bottom left) first and enter an admin’s details to make changes. Click Advanced and then the TCP/IP tab. Set the Configure IPv4 pop-up menu to ‘Using DHCP’. When connected to the router’s Wi-Fi network, the iMac should now get an IP address from the router’s DHCP server, as your other devices are doing.

In advanced network prefs, check the router’s IP address is correct and the Mac gets an IPv4 address using DHCP. Before setting up a new router from your Mac, note its IP address from its case label or documentation.