3 Devices Say "Unable To Connect" to FiOS Wi-Fi When Password is Correct!!

[ralph2018]

My FiOS Internet service was a MI424WR Rev I router. Everything worked no issues.
Then I upgraded to the new Quantum fios gateway router. Now 3 (2 of one type 1 of another different manufactures) of 10 wifi devices will not connect to the router.
We get password incorrect error? Was on the phone with tech for 2 hrs! No help. The answer is it's not the router.
Even though all devices worked on the previous equipment.
We have tried multiple items;
Like legacy settings - password change - SSID change individually and together. Router reset- device rests - just trying to connect the device that will not connect with nothing else connected etc.

We are not tech savvy so what can we do? Do we get a separate wifi device? Has anyone come across something like this?
In searching the forum I found the following;
https://forums.verizon.com/t5/Fios-Internet/Some-Devices-Say-quot-Unable-To-Connect-quot-to-FiOS-Wi-...
And another that was similar but it also had no answer as to how to fix.

[jonjones1]

You are saying in essence 3 out of 10 devices won’t or cannot connect to internet.

you have to take each device (one at a time) select the network SSID (name) and select forget this network. Turn the device on and off. Then select WiFi again. You should see the name of your WiFi network. Click on connect and then enter the password for your 2.4 or 5 Ghz network. Some devices connect to either or or both.

enter the password exactly. It should connect with no issues.

you are to enter the WiFi password from the sticker on the Quantum not the master password for router access. Look at the WiFi SSID and password and enter it exactly.

if you changed the password on the Quantum for WiFi it will have to be the one you changed to.

https://www.verizon.com/cs/groups/public/documents/adacct/fios-qgr-userguide1409251.pdf

[ralph2018]

Thanks for the reply

However we have done exactly what you have stated.  still no connection. 

the same thing password is incorrect. and no connection 😞

[kh-gary]

Hi ralph2018,

Your issue has been escalated to a Verizon agent. Please check your Private Message Inbox for a message from Verizon_Support. You can find your Inbox by clicking on your username at the top right corner of this page. Please direct all correspondence concerning your issue to the agents, who will be assisting you privately.