However, as I learned from Fujitsu Technical Support, to get a Wireless-N connection above 54 Mbps, you have to use WPA2/AES security and encryption.

Trying to keep your WiFi safe can feel confusing. There are a bunch of letters like WEP, WPA, WPA2, and WPA3 that show up when you look at your router settings. You might wonder what they all mean ...

However, if you have old Wi-Fi devices that aren't compatible with WPA2, you can use the TKIP+AES or "mixed" mode option if it's available on your router.

A WPA compliant device however can implement AES optionally whereas WPA2 compliant devices must be capable of both though you're not required to use AES.

Use WPA2-AES. It has the best security and throughput. There are scenarios where adding tkip decreases security, however it for sure increases compatibility with old crap.