This fixed my Bionic so the 4G stays BLUE!
Home>Settings>Battery & Data manager>Data Saver> Turn it OFF
Home>Settings>Battery & Data manager>Data Delivery> Turn ON Background Data AND Data enabled.
Go back to home. Power down your phone (Turn it off) .
Wait a minute then Power back on.
Since I've done this almost 24 hours ago I haven't lost the 4G LTE connection once. It stays BLUE.
Hope this helps all of you.