Can't use mobile data on Xperia SP

[wb195]

My Xperia SP C5306 had been working on T-Mobile's 4G LTE network well for the past 7 months.  Then all of a sudden it was unable to receive any mobile data.  I have reset factory settings, obtained a new SIM card, verified all APN's with the local T-Mobile store, and re-installed the software using PC Companion at the suggestion of XPeria care.  

All other functions, voice, messaging, wifi, are still working, but no mobile data.  T-Mobile said they were performing some maintenance and upgrade work on local towers, but my wife's iPhone 5 and my son's older Xperia Arc, as well as all of the phones in the local T-Mobile retail store, are still working fine with mobile data.  It has been a week.  Out of ideas.  Help!

[Alexander1]

Hi and welcome to the community! Since you're new please be sure that you have checked out our Discussion guidelines.

Do you experience any difference if you change the network mode under settings > more > mobile network > network mode. 

Try to change and see if you experience any improvement. 

[wb195]

Yes that was the first thing T-Mobile had me do, switch network mode from 4G/LTE to WCDMA only.  It seemed to work for a while, then dropped out.  Keeping it in WCDMA allows very intermittent data connections, only for a few minutes at a time.  I have contaced XPeria Care and they gave me an RMA to send the phone in for warranty service.