C7000v2

My modem-router has been giving me the flux for two weeks about 4 days ago I restarted the historically when i did a hard reset the genie window would pop up on one or more of my devices as the internet would be available but I would not have access to all the websites.  I am an Instructor who teaches online so this has been very frustrating.  When I logged into my PC the genie website popped up and i inputted my information it stated it was not connected.  I later found out genie is end of life.  Now I have no way to access my internet fully.  When I called he stated the modem was fine that it was DNS because i did not have access to all websites.  I have flushed the DNS and nothing has changed.  I have downloaded the nighthawk app and it cannot find my wifi network even though full bars.  

I am at a lost because I cannot access the full use of my internet and cannot complete whatever genie provided.  I need help....