whats so complicated?
USB3.0 can interfere with 2,4GHz WiFi as it uses same frequency, so if you enable "reduce 3.0 interference" it turns USB3.0 off and limits it to work as an USB2.0 and there should be no problems.
But you wont have 3.0 speed anymore!!!
Disabled you will have 3.0 but can make problems.
Newer router revisions have better shielding, so Merlin leaves it disabled in recent firmwares for better performance (speed), but for some it doesnt work.
But even with enabled I have the situation, that a stick wont work on 3.0-port regardless I enable or disable it, but working on USB2.0 port quite well ...!!!
At the end you could say, a great Asus marketing hoax, they sell things knowing that they dont work well and so graded down in their own firmwares by default!