My brother and I have both have the issue. With both have N6s on T-Mobile. Here are the issues I've had with texting:
- When someone sends me an SMS/MMS, I sometimes don't receive them. If they try again (within seconds), it comes through.
- When I receive a group texts (another form of MMS), I sometimes don't get them. Occasionally, I'll receive the sender's text in my individual thread with the sender and it says something like "Couldn't download MMS. Tap to retry". I tap. Sometimes it works and the message will be delivered to the group text. Most of the time it fails.
I have tried:
- A factory reset
- A new phone
- A different Messaging app (Hangouts)
- Deleting all APNs except the one I'm using
- A new SIM card
- Working with T-Mobile. Their "engineers" checked my network settings in the system and confirmed everything is set up correctly.
My conclusion is that there is something wrong with the Nexus 6 build of Lollipop since it seems as though this issue does not exist on a Nexus 5.