I’ve done this a few times already so thought it would be a good idea to document it. What this does is basically make a 2nd wifi spot using your original wifi.

1. Get the original modem’s ip address (usually 192.168.1.1) If not check by typing “ipconfig” in the command line on a computer that’s connected to the original modem’s wifi.
2. Disonnect from the original modem’s wifi and reset the 2nd modem to default. Then connect to it via ethernet cable through the WAN port.
3. Log into the 2nd modem by typing 192.168.1.1 into a browser. I like to change the wifi name to something else. Under “LAN” settings change the ip address to 192.168.1.2. Turn off DHCP. Save. The modem will reboot and kick you off the site afterwards.
4. Connect the 2 modems via ethernet cables in the LAN ports. Try connecting to the 2nd wifi. If good, move the 2nd modem to another location.