[anon(166548)]

I have the LG V35 (Amazon version), using it on AT&T.

Symptoms - the phone worked fine with my AT&T SIM before I took it out of the country, worked fine out of the country with a Three SIM, but now I am back I cannot get cellular data on it with the AT&T SIM in it (calls & texts work fine, as does Wi-Fi data). After trying a bunch of things, I broke down and did a factory reset.

That did not fix the problem.

I have several other phones on AT&T, and they are all working OK with respect to data connectivity. I put my SIM in a V20 and data works (implying there is not a problem with the line provisioning or the SIM). I put that other line's SIM in this phone and it failed (implying there is a problem with the phone).

I checked the APN after the factory reset and it is enabled and correct (compared to my other Android phones). All other settings are normal (mobile data enabled, mobile data usage not limited, 2G not disabled, did I miss any?). I tried Network settings reset - didn't help.

However, Settings > General > About Phone > Network has some odd items in it (in bold):
Network: AT&T
Signal strength: -118 dBm 22 asu
Mobile network type: LTE
Service state: In service
Roaming state: Not roaming
Mobile network state: Disconnected
IP address: Unavailable

Is there another setting (like in the radio or something) that survives a factory reset? Is there a chance that either Three mucked something up, or AT&T when I returned? I have used Three SIMs in other phones (Nexus 4, Nexus 5) in the past, and had no trouble getting those phones back on AT&T when I returned.

Not that this should be necessary, but I made sure that the phone was never powered up overseas with the AT&T SIM in it, so as far as AT&T is concerned the phone just disappeared for a couple of weeks, and then re-appeared.

Thanks.

PS: this is sort-of related to my post in LG V30 (AT&T) stopped locating itself regarding my wife's V30, however the symptoms are different, and the circumstances leading up to this are different. And hey, at least location is working on my phone (unlike my wife's V30 in the other thread)

PPS - should I be concerned that my working phone is on Band 12 (-106 dBm) while the "dead" phone is on Band 2 (-119 dBm)? (this info is from the LTE Discovery app).

[anon(166548)]

As an experiment I put my Three SIM back in this morning, which exposed a setting that I remember seeing on older (pre-LTE) phones, but that is not exposed with the AT&T SIM in - Settings > Network > Mobile networks > Network mode

After I put the Three SIM in the phone, the value of Network mode was 'null'. I selected GSM/WCDMA/LTE auto and the phone got data (roaming) on AT&T. I think it's HSPA only (hard to tell with the tiny icon on this phone, but that seemed to be what LTE DIscovery was saying).

When I put the AT&T SIM back in, that same setting (Network mode) is hidden. And I am back to no data service (Mobile network state: Disconnected).

Does AT&T have a way of blasting settings over the air (without a data connection)?

[B. Diddy]

Hi, me again. Is there a menu Settings>Networks>Mobile Networks>Network Operators? If so, does that correctly read AT&T? Or, if there's a switch for Automatically Select Network, turn that off and see if you can manually select AT&T.

[anon(166548)]

Hello again

Network operators only appears with the Three SIM in, it is hidden when the AT&T SIM is in.

With the AT&T SIM in, the Settings > Network > Mobile networks menu only has 3 items:

International data roaming (off)
Disable 2G (off)
Access Point Names (under which there is a single APN, the nxtgenphone APN)

With the Three SIM in, that same menu changes to:

Data roaming (off - I can turn this on and data roam on AT&T if I force that provider)
Network mode (Preferred network mode: null - I previously set this to GSM/WCDMA/LTE auto but it disappears (and is reverted to null) when I put the AT&T SIM back in)
Access Point names (under which there is a single APN for Three)
Network operators

and under that Network operators menu (visible only with the Three SIM) are:

Search networks (if I hit that it shows AT&T, T-Mobile, Verizon, I can choose AT&T and data roam (until my 30-day package runs out in a couple of days))
Select automatically (hitting this results in emergency calls only, I suspect it is defaulting to T-Mobile which has very poor service at my house)

When I put the AT&T SIM back in it reverts to the same three menu items I list at the top of this reply (and clears out the Network mode setting since when I put the Three SIM back in again it reverts to "null".

There's a lot I don't know about carrier settings, but clearly the AT&T SIM is hiding (and clearing) some of the settings, even though this is an unlocked phone.

Thanks for the response.

[B. Diddy]

Sorry if I missed this before, but have you already asked AT&T about this? I wonder if there's some method of reprovisioning the phone to make sure it's correctly on AT&T's network (although from what I recall, reprovisioning is generally for CDMA networks like Verizon and Sprint).

[anon(166548)]

I have been meaning to do that, but have not had a chance. Every time I try the chat support is unavailable, and I'm reluctant to sink a bunch of time into letting a phone support person follow a script while I respond "yep, tried that" to every step.

I'll probably try a walk-in at the local store. They've been pretty good in the past. But this is a little more tricky to wrap your head around.

[B. Diddy]

I think this is definitely your next step. This kind of thing does seem to crop up with some regularity, so hopefully the tech support person is familiar with it. It might help to ask if the phone needs to be reprovisioned (again, not sure if that's the right term for GSM networks -- but it might trigger the right response from support).

[anon(166548)]

I tried calling AT&T yesterday, she wasn't able to resolve it. I'll play CSRoulette and call again (or visit the store), repeating the word "reprovision" several times for good measure.

I tried LG Bridge, thinking an OS update might force it, but LG Bridge just tells me I'm up to date and won't let me force it :-(

I guess I could wait until LG issues another OS update (if ever) :-D