Samsung Galaxy Note 3 Neo SM-N750 was launched almost two years ago running on Android 4.3 Jelly Bean. It was later updated with 4.4 KitKat, and the 5.0 Lollipop update kicked off worldwide last January.
It seems the next major update for the Note 3 Neo won't be Marshmallow, but 5.1.1 Lollipop instead. The new firmware began seeding in South Korea since late October via OTA and Kies.
Now the update goes global and the first market to get it outside its home-country is Russia. Battery and performance improvements are expected, as are some critical bug fixes.
Oddly, the Galaxy Note 3 is still stuck on 5.0 Lollipop. There is no info if Samsung is planning to bring the Note 3 series up to Marshmallow or they will end being on Lollipop for good.