4G LTE MODE opens a secret menu where advanced network configurations can be selected.

Features -
*Change network to "LTE(4G) only" mode
*Phone will disconnect less often leading to FASTER INTERNET SPEED
*Enable VoLTE on supported devices(enables direct call over 4G network)
*Advanced network statistics
*Change network parameters
*Lock to any particular Network Signal like 4G(LTE)/3G/2G only

**Remember on some phones when only LTE mode is on, user can't make and receive voice call.
On some phones user can't send SMS after change settings.
If you have above bugs and restart phone don't help try set preferred network to first at the top of the list or Global auto, WCDMA or other network which support SMS and voice call in your country.