WGR614v10 as network extender, can't access control now

Have had this WGR614v10 for a couple years. Two years ago, it was configured to extend both my wired and wireless network (FiOs main router), using the same SSID for WiFi. My main WiFi is distant - signal near the 614 is quite low from the main system.

WiFi light is lit, but no signal as measured by WiFi Explorer on cellphone. Only a very low signal from the VZ unit is seen.

I cannot access the router control through any means I have tried. routerlogin address does not work, physical connect to addresses gets me the following:

192.168.1.1: reaches primary Verizon router (correct)
Any other address I have tried - "page not found"
If I am wired to main router, using the "routerlogin" URL, I get a web search result.

Disconnect router from network and use as a standalone, reboot PC and no address is supplied (expected this as the 614 is configured to get all addresses from the VZ unit), the PC will not connect as the router has not supplied a network.

How do I access this device to find out what is going on with the WiFi signal? All WIRED connections working 100% - only the WiFi part is in question, but I cannot access the 614 itself to see it. Do I need to reset to Factory Original to get back in and reconfigure the unit? Is there some other way to get into the 614, being as it apparently does no have it's own address on the network now, given the previous configuration?

Thanks.

JC