If everything else fails try to write in Odin (or better yet in Mobile Odin Pro) just the modem - and aim for an older version, something like MI6 (present in MI7 firmware) or MJ1. With Mobile Odin Pro you MUST be on stock recovery and it will work perfectly first time, with normal Odin there are some reports that you might need to write it twice or something like that - search around.
Did you test your sim card and make sure it is ok? Try to out this sim card into another phone and make sure it works? Put another gud sim card into your Note 3 and check if the problem still persist?
Dial *#0011# and check for the RX, TX value? Can you post this screenshot here?
So i've send in my phone for repair after it didnt work again (no network), they did not find anything and send it back to me. Then it all of a sudden worked for like half a week (I flashed Xnote B.15 right away ) Now i have the same error again, it suddenly stopped working again though i did not install/change anything...
I hope someone gets a solution for that, else ill say goodbye Samsung and Knox and hello Sony/HTC or w/e my next phone will be...