Samsung Smart TV 6820 series wireless connection to ASUS RT-AC66U

Hello - I have a Samsung TV 6820 series which has never had a problem connecting to my wireless network. That is, until I purchased a new router - an ASUS RT-AC66U. Now the TV will not connect. It can see my router, but when I select it and enter the correct password, the message returned is the the connection failed. It does not say that the user or password is incorrect, just that the "connection failed".

Wondering if anyone else has experienced issues connecting to their ASUS...

Samsung Smart TV 6820 series wireless connection to ASUS RT-AC66U