[Nexus 6 Q&A, Help & Troubleshooting] TaintedByte:
Did the same just now, and frankly, they have no idea that it's even an issue and are just passing the blame on. It's not a T-Mobile specific issue since other users are having issues on Sprint and I believe one even on Verizon. My chat rep insisted the issue was my SIM card even though I told her repetitively that it was okay since it works fine on my Nexus 5.

Here's the transcript:

[b]My issue:[/b]
Nexus 6 was working fine until three days ago, no software changes were made to it. Suddenly it would drop
data connection and a ! would appear by the data icon. Nothing fixes it until I reboot the phone, then it's
only a matter of time until it happens again. It's not a carrier issue as there are reports of this happening
in Sprint and Verizon as well (I have T-Mobile).
More reports of it happening here: http://goo.gl/NN5x8H and here: http://goo.gl/12UoIc

[B]Google Support	7:10 PM[/B]
You are now connected to Katie C. Please type your message and hit 'Enter' to send.

[B]Katie C	7:11 PM[/B]
Hey Jon! Thanks for getting in touch with Google. My name is Katie. Thank you so much for waiting!

[B]me	7:11 PM[/B]
No problem

[B]Katie C	7:12 PM[/B]
I see that you're needing help with your data connection dropping. I'd be happy to help you out with that!

[B]me	7:12 PM[/B]
Thank you

[B]Katie C	7:13 PM[/B]
Before we can try some specific troubleshooting, have you first tried ejecting the SIM card and cleaning it?

[B]me	7:14 PM[/B]
Yes I did all the obvious things. Please read my message, it's not just me, it's a widespread issue happening to
multiple people, on multiple locations and on different carriers. I already went and talked in person to my
carrier, they also confirmed that it's a Nexus 6 specific issue as they had two others before me ask about
it in the past couple of days.

[B]Katie C	7:15 PM[/B]
When you spoke with your carrier, did you get a new SIM card?

[B]me	7:16 PM[/B]
SIM card isn't the issue. I still have a Nexus 5. Put the SIM card in it, it works fine.

[B]Katie C	7:17 PM[/B]
Do you mind waiting a minute while I look into this a bit further for you?

[B]me	7:17 PM[/B]
No problem.

[B]Katie C	7:19 PM[/B]
Is your Nexus 6 rooted or running a custom ROM?

[B]me	7:20 PM[/B]
Yep, both. Not the issue either since it was working fine until about three days ago.
Also, just to be thorough I went fully stock to the latest 5.1.1 image, issue persists.

[B]Katie C	7:21 PM[/B]
So you've completely unrooted your device?

[B]me	7:22 PM[/B]
Yes. It's 100% stock.
Here's what my status page shows, if it helps: [url]http://i.imgur.com/ockFC7x.png[/url] (notice the network state is 'connected')

[B]Katie C	7:22 PM[/B]
I would recommend contacting your carrier again and requesting a new SIM card.
Very often replacing the SIM card resolves this issue.

[B]me	7:22 PM[/B]
Okay, it's not the SIM card though, if that's the case it would not work on my Nexus 5.

[B]Katie C	7:23 PM[/B]
I would still strongly recommend replacing the SIM.

[B]me	7:24 PM[/B]
The point of failure is the phone, though, not the SIM.

[B]Katie C	7:24 PM[/B]
In order to confirm that, we'd need to replace the SIM.

[B]me	7:24 PM[/B]
How is that the case? I'm using the same SIM card on a Nexus 5 with zero issues.

[B]Katie C	7:25 PM[/B]
The only other step I have would be to look into your warranty options. Where did you purchase your device?

[B]me	7:26 PM[/B]
Through Google Play.

Our only hope is that Google fixes whatever mess they made and seeing as this is only affecting a small portion of the Nexus 6 users, that isn't looking so good.