Cannot connect to a data connection on Sprint HTC One M8 Firstly, I am running CyanogenMod 12.1 on my HTC One M8, but this is an issue I also experienced running stock Android (e.g. Lollipop).

The issue I am experiencing is that my device appears to be unable to reconnect or "get back" on the Sprint data network. For example, yesterday, I was in NYC (obviously somewhere that should and is covered), but I was unable to get a data connection anywhere in the city. I was only able to send SMS (not send/receive MMS) and make voice calls.

In the past, when I had this issue on Sprint, being the helpful individuals they are, they told me to restore my phone and reinstall Android. I did that, which helped for a while, but it wasn't long before I ran into the same issue on stock Android. After a while, the issue seemed to "resolve" itself magically. I never found out why or how.

More recently, I rooted my phone and installed CyanogenMod 12.1 on my M8, and I am running into the exact same issue I had before. Ideally, I don't want to have to restore my phone again, because not only do I not think this is the "fix-all", but it seemed like Sprint's lazy answer for not wanting to actually troubleshoot my device.

This is becoming increasingly apparent when I travel as I am unable to get GPS directions, send MMS messages, or do anything over data like normal when I'm off of a WiFi network. Despite having "bars" on my screen, CM will display a small "!" over my data icon, which I assume is an indicator that it is unable to connect to the mobile network in some way.

Is there anything I can do to better troubleshoot my mobile data connection?
The same thing happened to me after I rooted and installed CM.

I seem to have just solved it by going into the Access Point Names menu, opening the 3 dot drop down menu and selecting "Reset to Default" and rebooting the phone. I then went back into said menu, clicked the add (+) button and entered a new APN with the settings as follows:

Name        : Sprint
APN         : cinet.spcs
MMSC        : http://mms.sprintpcs.com/servlets/mms
MMS Proxy   : 68.28.31.7 6
MMS Port    : 80
MMC         : 234    
MNC         : 15    
APN Type    : Internet + MMS
APN Protocol: IPv4


I left every other field blank, saved it, selected it from the previous menu and restarted. Everything seems fine now, I've got full LTE where I had sporadic 3G (mosty no signal) in this same spot just moments before. Granted it's only been an hour so time will tell.

Source (and steps for some models): 4GTricks - Sprint APN Settings For Android, Samsung Galaxy, HTC One, Xperia, Motorola Moto, LG G1