LineageOS 14.1 (Android 7.1.2) "deep post" for the Samsung Galaxy Tab E (gtel3g/SM-T561) refers to a specific unofficial build released around April 19, 2018
If none of the above fixes work, you may need to perform more advanced troubleshooting: lineage14120180419unofficialgtel3g fix
Here's a story based on this information: LineageOS 14
Alex spent the next few hours exploring every nook and cranny, testing games, watching videos, and even doing some productivity tasks. The performance was smooth, and the battery life seemed improved compared to his previous ROM. lineage14120180419unofficialgtel3g fix
Once you have applied the "lineage14120180419unofficialgtel3g fix", the device will be usable but slow. Here is how to optimize it:
Root / Magisk issues
GApps and Play Store problems