Glad it worked for you. but just because it worked is not the best option. My Echo gets on my "regular" 2.4 signal as well as on my Guest signal and they are set up exactly the same except for the passwords.
A few years ago when I set up my dual-band N router that replaced the old trusty G router, I quickly discovered that setting up the new router's various wireless settings was a foreign language to me. So I dug in and did some research. I experimented with various options. I found that to make the router work with legacy G and even B devices there was a price to pay in speed and security.
Since our house was now full of newer laptops, numerous mobile devices like iThings, Kindle tablet and other similar gadgets (that keep appearing!), they all had one thing in common. They were all N devices. We really were not using older devices anymore.
So, at that point, I settled on restricting the router to:
Wireless Mode setting of "N Only" goodbye to anything less
Authentication Method at the highest level of: WPA2 Personal
Which then enabled me to set the highest level, of
WPA Encryption to only be AES
Both 2.4G and 5G use these settings.
It's been set this way for a few years now, and no more experimenting with settings. It works great for our gadgets and for everyone with N gear who visits us. And remember, these settings maximize the performance of N gadgets so they attain their full wireless speed and security potential when on my network.
Want more info and proof: just Google for AES vs PSK and the first few articles help to understand this stuff.