changed the upper antenna connector. lower antenna/dock/headphone 3 times. each time i replaced the lower, the network worked for a day or less. a darn shame. iphone 6 was too good to be true.
Update (01/25/2017)
darn it. this is possibly temporary but this worked. for now at least. and dont blame me if something else happens. i took the risk as well. anyhow.
shut down phone.
remove sim card.
place phone in protective case.
drop on a sturdy hard table onto its backside from 12 inches high.
re-insert sim card.
Boot up your phone and see that glorious LTE.
its going to be awesome to wake up to "searching" "no service".
this is clearly a design flaw with the IC Chip that connects the antenna/networking system.