Nexus 6 on TMO Fix

From any Home screen, tap the All apps key.
Tap Settings.
Tap More.
Tap Cellular networks.
Tap Access Point Names.
If available, tap the T-Mobile US APN (the bullet point fills with green). If not available, tap the Menu key, and then tap New APN.
Note: To reset your APN settings, tap the Menu key and then tap Reset to default.
Verify and update the following settings for the Data APN:
Name: T-Mobile US LTE
APN: fast.t-mobile.com
Proxy: <Not set>
Port: <Not set>
Username: <Not set>
Password: <Not set>
Server: <Not set>
MMSC: http://mms.msg.eng.t-mobile.com/mms/wapenc
MMS proxy: <Not set>
MMS port: <Not set>
MMS protocol: WAP 2.0
MCC: 310
MNC: 260
Authentication type: <Not set>
APN type: <Not set> OR Internet+MMS
APN protocol: IPv4/IPv6
APN roaming protocol: IPv4
Enable/disable APN: <greyed out unless there are multiple APN's>
Bearer: Unspecified
Tap the Menu key.
Tap Save.
Tap the desired APN profile you want to use. The bullet point fills with green next to the APN profile.
Tap the Menu key.
Tap Save.
Tap the desired APN profile you want to use. The bullet point fills with green next to the APN profile.