If you have updated your unlocked Galaxy Note 4 with Android 5.1.1 OTA update (N910CXXU1COH4) that Samsung rolled out for users in Poland, and are currently looking for a root method, you might consider using the root package by senior XDA forum member, geiti94.
However, to use this root, ensure that your phone has Android 5.0.1 bootloader, otherwise you will encounter infinite bootloops. Also, keep in mind this root removes Knox security, installs SuperSU, Buxybox and 5.0.1 modem.
The member further warns users not to use this root package as it installs 5.0.1 modem for Note 4 N910C model. Also, before jumping directly to root Galaxy Note 4, ensure that your phone meets the following requirements.
How To Root Galaxy Note 4 On Android 5.1.1
Now, please make sure that you follow all the below steps in the correct manner as they are outlined. However, if you don’t, you might on the long run find yourself bricking your phone.
Step-1: Download the flash-able root package and transfer it to the storage of the phone
Step-2: Download Android 5.0.1 bootloader package. Extract it using any extracting tool and you should find a folder containing Odin flash-able tar package and Odin binaries
Step-3: Put your Note 4 into Download mode
For this, first switch it off
Press the Volume Down, power and Home buttons together until a warning screen appears with an Android logo
Press Volume Up button to confirm entering into Download mode
Step-4: Connect your phone with the PC via USB cable
Step-5: Double click Odin3 v3.09.exe file to open it
Step-6: Flash the bootloader. Click BL button in Odin and load the bootloader file and click Start
Step-7: When the installation is completed, reboot the phone into recovery mode
Switch off the phone
Press and hold Volume Up, Power and Home buttons together until the Samsung logo appears, then release the Power button while holding the other two until the recovery menu appears
Step-8: In recovery mode, select Install and locate the root package which you have saved in the phone’s storage
Step-9: Upon installation of the root package, reboot the phone.