HP LaserJet Pro 200 Color MFP M276nw will not wirelessly connect to a ATT Fiber BGW320-500

[DJWhirl]

I have a new router and am trying to connect the HP LaserJet 200 colorMFP M276nw to the network. The router is a BGW320-500 from ATT (fiber). The printer finds the SSID and I enter the password to the network, which I have successfully used in all other devices in my home with no issues. I know with 100% certainty that the password was entered correctly. I get the error “Invalid WPA passphrase”. I have reset the router and reset the printer to default settings, many times. I always have the same issue. I have seen many people with the same issue but have never seen a definitive solution to this problem. I have successfully used this printer in the past with a different router, so I know it can work. Can someone please help?

What I have tried:

1. Reset ATT modem back to factory defaults

2. Reset HP Laserjet Pro 200 back to factory defaults

3. Did NVRAM reset on HP Laserjet Pro 200

4. Changed ATT Modem wireless settings by disabling 5Ghz wifi channel, changed the 2.4Ghz wifi channel from "AUTO" to channels 1, 6, & 11 to no avail. Changed all the security as well, nothing. 

The "ONLY" reason I am doing this is because I CANNOT "AIRPRINT" (to a wireless device such as an iPhone, etc.) if this printer is NOT setup using wifi only. If I use and ethernet cable, "AIRPRINT" is disabled and does not work. 

[DJWhirl]

Also, tried WPS...not working.

Tried to use a PIN instead.....not working.

Completely disabled the encryption and hid the SSID....BINGO!!!! It is now connected.... but in an unsecure state (which is NOT acceptable)!