Ring Door Bell 3 Pro will not connect to Router

Ring Door Bell 3 Plus - attempted to install today and after going thru setup for WIFI Connection, when I attempted to connect to Wifi - I was able to select the network I needed to connect to - signal strengh on my phone for that network was very good, but everytime I went thru the setup process, it failed - the final connection step where it says "Ring Doorbell is trying to connect to your network" failed every time - with the lights on the doorbell flashing (two lights on the right side) were flashing - and ultimately, the doorbell wanted me to try again. I did this at least ten times and it failed everytime. I even brought the doorbell into the house and attempted to set it up while sitting within 5 feet of the router and it failed. (Meanwhile, I can easily connect my phone and PC to that router and get a great internet connection each time. The Router is the Netgeat 1900 - a pretty standard router that I am using to extend the Wifi Single in my house. Works great when any other device I own needs to connect - but will not connect to the Ring Doorbell 3 + ????? I am at a complete loss ???