I can give you custom steps to get the most performance out of your hardware. Share public link
Because Android 5.1.1 is an older OS, some security patches released during that era closed the loopholes that these apps exploit. If the methods above fail:
There are two main paths to root Android 5.1.1 without a PC. You must choose based on your specific device model. root android 511 without computer new
It analyzes your device model and version to deploy a specific exploit. It is known for having a high success rate on older Samsung and Sony devices. 3. One Click Root
A green checkmark or a success message will indicate that the root path was successfully deployed. Method 3: Rooting via One Click Root APK I can give you custom steps to get
If supported, select "Root Device" to initiate the automated script execution. How to Verify Your Root Access
However, remember that root access is powerful. Be careful when granting permissions to apps, and never modify system files unless you are absolutely sure of what you are doing. Enjoy your newly unlocked Lollipop device You must choose based on your specific device model
If you cannot achieve root without a computer, you will need to utilize a PC to flash a custom recovery (like TWRP) via ADB/Fastboot or Samsung Odin, and then flash the (the final version supporting Android 5.0+). This method is significantly safer and more permanent than using legacy one-click utility applications.
Safer than 2015, but still risky.