I recently had Verizon internet service installed via a Verizon Tri-band 4x4 Router router (Model G3100)

I have been completely unable to access my router in order to modify the configurations. Per the instructions in the user manual (and online), I should be able to access/ configure my router following two URL’s: mynetworksettings.com or https://192.168.1.1 However, neither of these work. I have tried on several different devices connected to my Fios network and in every case the page in unreachable.
I also tried the Admin URL listed on the router (myfiosgateway.com) and got the same result.
I have tried resetting the router to factory settings and no dice.
Any suggestions?