Pixel 3 losing data connection after disconnecting from WiFI

I have the same experience. It's not the disconnecting from WiFi that triggers the issue. That's just when I happen to notice it. I don't send a lot of MMS, so I typically don't notice the issue while I'm at home. It definitely happens at random times though. I'm also not using WiFi calling.

I'm afraid it's looking like I'll need to RMA the phone.

@willwhitworth, @stpark6985 I'd try another "Network Reset", under Settings->Connectivty..., before I did an RMA.

Also, have any of you called CS, and asked the to "re-provision" your phones?  This can often fix things like this too, since the phone has to rebuild the LTE settings, as a result.

Sometimes you have to get to a 2nd-level tech, to get a re-provision done, IME.

I don't suppose any of you has access to a SIM from another carrier, that you could test, briefly?  From what you're describing, it sounds like it'd be a very quick repro (or not).

What you're describing sure sounds like a s/w issue to me, not a h/w one, but I suppose it's possible (most of my dev/design work has been on testing interfaces that span both sides) that all your phones have a bad modem chip or something, I guess...

pgrey, I missed some of your questions so I wanted to answer those here.

The Preferred network type options on the Pixel 3 are LTE (recommended) or 3G. Mine is set to LTE (recommended).

WiFi calling does work fine on this phone. I even tested it in Airplane mode and I was able to make a call. It indicates on the call screen that it is a WiFi call. Like I said in my previous post, I don't normally use WiFi calling, so that isn't related to the issue we're having.

I did try another Network Reset, but that didn't fix the issue.

I did contact CS and asked them to verify the IMEI on my phone matched what they have on their end. They confirmed it did. I also asked them to re-provision the phone. That didn't help either.

I don't have access to a SIM from another carrier, unfortunately.

I completely agree that this appears to be a software issue, but I'm at a loss at this point. I'm just glad I found some other people having the same issue. I thought I was going crazy.

@willwhitworth I really think this is WiFi calling-related, in fact I'm almost certain of it. But, there's no great way to tell, that I know of, except using a debug mode module, or ADB.

Did you set the "calling preference" that @lizdance40 mentioned, to "LTE Preferred"?  It should work, in either mode, but using LTE as the primary may prevent the phone from getting "stuck" on the Voice/Text-over-WiFi "mode".

There's a tool that I use, when I want to check my LTE towers nearby and signal and such, that *might* help here, called "Network Cell Info Lite".  It will show which tower(s) you're on (you have to get the paid version to show more than 1 + secondary, but the free one works fine for most applications like this), and when a transition happens, from VoWiFi to VoLTE, it has a full page of nothing but those stats, the "Device + SIM" page, specifically.  While not exactly a "debug tool", it should show your transition, between the two.

It WILL drain your battery like crazy though, if you leave it running in the background, indefinitely, but the dev has handily put in a switch (power-symbol at top) to turn this off, when you're not using it.

Now I really wonder, how/why @lizdance40 has a working provision, with her phone, and the rest of you don't. I agree, it's coming close to the "at a loss" category, without using something like ADB, to track the transitions (a whole different can of worms), I'm hoping that the above tool will yield some useful data, at the least you should see the phone "trying to move to VoLTE", and failing.

The tool might show that the LTE signal isn't sufficient when the WiFi signal falls-off, which would explain a call dropping, at that point, but then it should "recover", and move to data from LTE (not the LTE with an "x").

I'm betting that AT&T has a bug in their server-side hand-off here, where it *should* be transitioning off your WiFi (as you leave your home or whatever), and still searching for another WiFi signal to "latch onto", but it should also be moving to LTE as a "backup", in the meantime, all without the user ever knowing about the various transitions.

That app uses a lot of data too.  But it does provide information.  Take screen shots on all tabs then shut is down to analyze.  

I have 2 used phones, no problem,  I don’t think it’s a carrier problem.  

Curious to see what the app yields.

Also curious to see what everyone has their default on the SIM set to for calls (also applies to SMS/MMS), "WiFi preferred" or "LTE Preferred".

I just had a thought, too, do all of you have your SIM "Data Roaming" set to "On"?  If not, this can be an issue, given that AT&T often uses "rented bandwidth", from other carriers, to bridge areas of low/no coverage.  This is pretty much transparent to the user; I wish they'd have some sort of explanation on that switch, about "domestic roaming".

Really, if you're in North America, there's no reason to have roaming set to "Off", except for a few of the older plans, where "straying" into towers in Canada and Mexico might cost you some roaming data charges.  

All the Unlimited, some of the per-Gig plans, and all the prePaid plans all support what's essentially "free roaming", in both CA and MX.

If you have an old plan, that's not inclusive of NA roaming, there are some "tricks" to getting it added to your account, usually at no charge, we can point you off to some other threads there, several of us have "guided" people through this previously...

Here is everything I've tried so far without success in order with testing done in between:

1. New SIM

2. AT&T support re-provisioned my device on the network

3. Reset android network settings to default

4. Tried manually configured NXTGENPHONE APN

5. Turned off WiFi Calling (there is no toggle here for preferring mobile over WiFi, its set to Mobile by default)

6. Turned off "Enhanced 4G LTE Mode" (VoLTE)

7. Factory reset

Just for reference, I don't have any dropped calls issues, call quality issues, or problems with LTE when its working. Also, I would agree that its not just when I'm disconnecting from wifi, but that's when I tend to notice it as I no longer am getting emails or other notifications that rely on the internet. I guess next step would be to run the app you mentioned above or use ADB when its stuck without LTE.

Did anyone get a chance to run that app or use ADB to see if they can pinpoint the issue? I thought it had fixed itself with the Feb security patch but it started up again over the weekend.  There's no rhyme or reason to when it will happen either.  Airplane mode still fixes it however.  Just annoying.