The file lineage-14.1-20180419-UNOFFICIAL-gtel3g.zip refers to an unofficial build of LineageOS 14.1 (Android 7.1 Nougat) for the Samsung Galaxy Tab E 9.6 (3G version, model SM-T561), codenamed gtel3g.
The string provided is: lineage14120180419unofficialgtel3g. lineage14120180419unofficialgtel3g fix
for root access, as built-in SU was removed in later unofficial iterations. Recommended Installation & Setup The file lineage-14
Understanding the Build: lineage-14.1-20180419-UNOFFICIAL-gtel3g The only downside is a broken GPS lock
Some developers ported the 20180419 fixes to Resurrection Remix 5.8.5. If LineageOS 14.1 still fails, flash RR-N-v5.8.5-20180614-gtel3g-Unofficial.zip. It contains all the RIL and MAC address fixes pre-baked. The only downside is a broken GPS lock (which also affects the Lineage build).
If you are having trouble with the 2018 build, community developers have released newer, more stable versions:
The Fix: This usually happens if the existing Vendor partition is outdated.