I setup my home network to have separated name (SSID) for 2.4Ghz and 5Ghz Network.
When I connect to the 2.4Ghz channel, no problem.
At the same distance, like 6 inches away from the router, when I connect to the 5Ghz channel, my 2 Galaxy Note 3 shows the same "network too slow" error and it will drop the connection.
This is one of the many reasons I returned my GSN 3
I also experienced another WiFi error.
At work, I can connect to the WiFi network with the WPA password provided, on my HTC One with no issue whatsoever.
When I tried to connect to the same network using the Note 3, it keeps telling me I have to "sign-in", when I click on the browser to "sign-in" (like those Free WiFi you can get at the hotel), there is no sign in page (because there is none) and brings me right to Google.com.
After that, the connection will last for 30 seconds or so and drop off.
The one I got initially and the replacement, both have the same issue, and I did inform T Mobile before I return them back.
4.3 problem? Samsung's problem? I don't know... All I know is I will wait until they resolve all these before I will reconsider getting this phone.

