Ring Doorbell

Please help me and keep simple as I am elderly and have no other help.

I use Nighthawk AC1900 R6900P with Ring Doorbell which had been working fine and now it does not.

Ring support helped to discover that the Ring app shows my network but will not connect. Range is fine and so is password. They had me setup a hot spot and that connected right away. 

I have started over with the Ring and during setup, it finds my network and after I get to 95% after entering password, it fails. I have the right password.

I been trying to fix of and on or more than a month and I am frustrated. My ISP did a reset and it did not help, I will assume that I am missing something really simple.

I am sure about password being correct and being within range.

Please help me with simple step by step instructions.

Thank you in advance for your consideration.