Avoid shady “firmware download” sites that ask for surveys. Only use XDA or trusted mirrors like AndroidFileHost.
After thorough research, there is no official or stable custom firmware (ROM) that brings Android 7.1.2 (Nougat) to the Samsung Galaxy Tab 2 10.1 GT-P5100 . The last official firmware from Samsung was Android 4.1.2 Jelly Bean. However, the development community (especially on XDA Developers) has produced unofficial ROMs that claim Android 7.1.2. These are often experimental, buggy, and not suitable for daily use. The best stable custom ROM for this tablet is Android 4.4.4 KitKat or Android 6.0 Marshmallow (LineageOS 13). download samsung tab 2 101 gtp5100 android 712 firmware best