I have root and am well aware that Samsung/AT&T have left their Note 8 model out to dry in terms of an official update. Are there any custom ROMs available? I quickly looked into installing TWRP or CWM recoveries, but came up with nothing. CM11 only lists the 51xx models as well.
Look in the Developers thread. There is now a great 4.4.2 ROM for the i467M, which is the Canadian version, with a good custom kernel. Everything works, wifi, LTE etc.
However, if you have the AT&T version, I think your problem is not the ROM, it's the locked bootloader.
|custom rom, i467|