Greetings
I had a previous problem unable to connect my Fire TV to my network, either by wi-fi or cable. After going through 4 units with the "help" of Amazon support, they eventually gave up & let me keep one. We got two Echo Spots on Friday & I was also unable to connect those. Just a refusal to connect to Wi-Fi, no matter which type of encryption used. (My profession is in computer support.)
My house does not have a TV licence & I am "legally licence free". Never watching any live TV, Sky or using iPlayer. I watch Amazon Prime exclusively.
In order to ensure that I am able to pass an enforcement inspection, I blocked "bbc.co.uk" on my router. (I had told Amazon support of this fact). I have now found that unblocking BBC on my router allows immediate connection for both my Fire TV & Echo Spots. I assume that the Amazon units must ping the BBC to confirm Wi-Fi connection & fail with no error when this is not possible.
As this issue is entirely undocumented, I hope that this post may help someone in the same position.