
Samsung Galaxy Note4
The latest firmware for Samsung Galaxy Note4 (SM-N910F) is N910FXXS1PPF1 with Android 5.1.1 (Marshmallow), released on June 7, 2016 for 1 region (CSC). Every official firmware build for SM-N910F, newest first: one row per build with all regions (CSC) that received it.
SM-N910F started on Android 4 and has received 1 major Android upgrade; it now runs Android 5.1.1 (Marshmallow). The newest build, N910FXXS1PPF1, was released on June 7, 2016. No new build has appeared for 126 months, so regular updates for this model have most likely ended.
Box codes of SM-N910F for different colors and markets. Firmware is chosen by the model code SM-N910F and your region (CSC), not by the SKU.

SM-N920AZW

SM-N920VZW

SM-N950UZK

SM-N920AZK

SM-N950X

SM-N930V

SM-N9300

SM-N930S
The newest firmware for SM-N910F runs Android 5.1.1 (Marshmallow): build N910FXXS1PPF1, released on June 7, 2016.
The latest build for SM-N910F, N910FXXS1PPF1, was released on June 7, 2016 (10 years ago).
SM-N910F has had no new firmware for 126 months, so regular updates have most likely ended.
Yes, all firmware files for SM-N910F are 100% official, original, and obtained directly from Samsung servers.
To flash SM-N910F, you need to download the appropriate firmware, put your device into Download Mode, and use the Odin tool to load the BL, AP, CP, and CSC files.
Downgrading is only possible if the bootloader version (binary bit) of the old firmware matches the current one. Always check the binary version before flashing SM-N910F.