Troubleshooting my mobile internet, because no one can figure it out

[WizardStan]

My phone will, periodically, lose its internet service. When this happens, voice and text services continue to work without a problem. Signal strength remains reasonable, around -70dBm. Rebooting my phone, cycling airplane mode, resetting my APN, these have all been suggested and they do not work. I simply have to wait it out, something that can take upwards of 30 minutes, during which time I usually do not touch my phone, it just sits there until the internet comes back, kind of like me.
Has anyone else ever experienced this behaviour? Do you have any clues as to what may cause it?
I have called my carrier during these outages and they tell me they can't detect any problem. Other people in the area on the same carrier as I am do not have this problem, at least not at the same time as I am. Assuming I root my phone and can have a peak under the covers, what might I investigate to start finding out? Any thoughts at all?

 

[NutNut]

Random: check/reseat your sim card.

 

[WizardStan]

Yes, that was also tried. What would that do though that would prevent the internet from not working but allow voice and text? If there's something wrong with the card you'd think it would just fail the entire thing.

 

[levi]

Is it still on 3/4G when this happens? Cos voice and text over 2G work just fine, but I doubt anyone supports plain 2G data any more, and GPRS didn't come till 2.5G or something.

Although that's all European GSM stuff. You're in NA, aren't you Stan? Does your phone even support old CDMA these days?

 

[Pocak]

More random:

• How are your IP settings? Can you force a new DHCP lease? How does a traceroute look? And do you get a complete blackout or just very high packet loss?

• Try changing the service type (2G, 3G, etc) for data packets.

• Check with an app (or with AT commands, if you're hardcore) which cell the modem is camping on, and if that changes when the 'net finally comes on. If so, moving around could get you back online quicker.

• Have you been pronouncing the incantations exactly when making regular animal sacrifices to your ISP overlords? Any sloppiness could doom us all. /jk

 

[NutNut]

More random stuff: check/update PRL if applicable, & check/change roaming settings.

 

[benoitb]

When it happens again try to reach a known IP to define if this is dns related or not.
If the direct ip works, use a dns not from your operator.

 

[WizardStan]

Is it still on 3/4G when this happens?

My carrier only supports 3.5G. If my connection reads "home" (which it does), it means I'm connected to one of their towers so must be HSDPA. If I'm roaming I don't get internet anyway.
Many good suggestions guys! Thanks! I'm kind of hoping it happens again soon so I can try some of them out and be all "see, I told you there was a problem with your system!" I'll let you know the results, may take a few weeks.

 

[Christoph.Krn]

This is probably obvious, but considering the things that you've already tried with this particular phone, you could try carrying another, ideally different device with you (if you can), just to see what happens when you swap the SIM card into there the next time this occurs.
[doublepost=1479583159,1479582614][/doublepost]Wait... I've never heard about connections that say "home" when you're connected to one of your carrier's towers. I only know this as "home" zone, as in "home" is displayed to indicate that you're detected as being in a specific geographic area, usually your literal home, where your contract then has different conditions. I'm in Germany though, I don't know about the US. Still, are you sure your contract is what you think it is?

 

[FBnil]

You could live in-between two cell towers. Then your phone suddenly switches to the other tower, and the calls would transfer, but your IP address gets stuck in the other tower (i.e. you stay registered at the other tower, to which you are not connected, and the system only allows 1 access, for which you need to wait for a timeout before you can re-connect)?


A cellular network is composed of many different cellular towers that your phone communicates with in order to make a phone call. Your phone automatically connects to the nearest tower when you're making a call and continues to communicate with that tower as long as it remains the closest one in range. If you're on the move though, whether walking, driving, or other, then you'll likely move out of the range of your closest tower and a handoff will occur to move your call to the new closest tower. Most of the time this handoff will occur without a problem, but occasionally there will be a complication and your call will be dropped during the handoff. That complication could be due to extreme cell traffic on either one of the towers, glitches in the backend software, power outages, and more. These are all problems on the side of the carrier, and while an inconvenience, you're usually able to make your call again without problem.

Maybe this trick works to indentify your tower:

https://community.verizonwireless.com/thread/735676

Then try it after you lose internet connection and see if it still is the same tower.

 

[levi]

I don't know 4G that well, but GPRS and WCDMA (3G) were designed carefully to ensure connections were transferred seamlessly between towers, and I'd be amazed if they didn't test alternating back and forward between two towers rapidly - it's an obvious stress test.

But yeah, checking which cell you're in is worth doing. Perhaps there's a rogue cell tower out there that is misconfigured.

 

[TeDaDeS]

I miss some information, like what phone/firmware and provider and such.

Recently had a lg nexus 5 with android 6.0.1, it could not always find the simcard, It was totally random, but searching google with the issue and specs I found (a lot) more people with this issue.

I would put the sim in a different phone and see if you still have the issue. If so you can rule out your own phone.
You didn't recently change anything to cause the problem?

 

[levi]

My phone occasionally (like maybe twice a year) fails to find its SIM card, but that stops everything when it happens - can't call anyone, can't text. I usually end up yanking the battery, and on booting back up even without touching the SIM card it's fine, so I don't think it's a physical problem, perhaps it's something to do with the phone processor and the one on the SIM card interacting in undefined ways once in a blue moon. But either way, I don't think it's Stan's problem.

 

[WizardStan]

You didn't recently change anything to cause the problem?

This isn't recent, it's been happening for years, through two phones and many iterations of Android.
It's not a problem finding the sim card, I've got full connection with voice and text, just no internet for some reason. Is very strange. My googlefu fails me, as all search terms I've tried just lead me to people who have never had internet on their phone, with simple solutions about adding the APN or not realizing they'd gone over their data cap (I've got an unlimited plan, so that's not it either); can't find anyone else with this particular "internet occasionally stops working for 10-30 minutes despite having perfect signal" thing.

 

[_jr_]

I have similar symptoms with 3G on my N900. It seems to happen when the modem returns to its low power state, but for me can be solved by a reinitialization of the modem (switching to 2G and back is enough). It's probably a different issue, since yours persists after a reboot. Though both might be bugs in the modems rendering them incompatible with current cell tower software.

 

[Eight Bit]

Phone and text messages are in a way different frequency area than data. I looked it up and GSM is (in the Netherlands) in the 880-890 MHz and 925-935 MHz range.
Data, 2G, 3G and 4G are in the 800MHz, 900 MHz, 1800 MHz, 2100 MHz or 2600 MHz range, depending on the provider. As you might know higher frequencies travel through matter less well than lower frequencies. Maybe that's the culprit in your case, especially when you are not so close to the antenna/transmitter. Your GSM signal could be in the lower regions of the spectrum while data is in a higher one.

For instance, I work in a concrete built, box in box concert hall.
Inside there's only one provider that penetrates the hall with their data signal, all others which are on higher frequencies have zero to none reception inside while regular GSM is no problem.

Did you try a provider with the data network in a lower frequency range?

 

[levi]

GSM is a catch-all term for 1G-4G - they're all technologies specified by the GSM. IIRC with 2G, GPRS was added at a different frequency, but from 3G and up, data and voice, text etc. should all go on the same frequencies as I understand it.

 

[ElPoco]

Check:
- Which network you're using (2G/3G/4G), you can try forcing the use of one of them to help check if it happens with all networks or only with some
- Which cell tower you're connected to, and the associated informations. Some years ago you could get plenty of information on Android without the need to root the device, there should be some applications that do it.

With this, you might be able to get a pattern.

 

[Eight Bit]

GSM is a catch-all term for 1G-4G - they're all technologies specified by the GSM. IIRC with 2G, GPRS was added at a different frequency, but from 3G and up, data and voice, text etc. should all go on the same frequencies as I understand it.

I don't think so but we might have the same term for different things.
My inlaws have a house in rural germany with perfect voice and text reception but only Edge data when lucky (mostly it's GPRS). I have to walk up the hill to get 3G reception, for 4G I have to drive to the next town. Last time I was there I found that Telekom.de had the best data reception at that particular location but as I was roaming I had the liberty of switching network to try them all out as I seen fit. That won't work at home.

But this is only possible if the two are on seperate frequencies I'd logically assume?

@WizardStan are other people who live near you, on the same mobile network affected aswell? Is the phone set to connect 3G only or will it try other networks when it can't find or lock on to 3G?

 

[ElPoco]

In 3G, data and voice don't go through the same network (even though they use the same channels), voice is still circuit switched in 3G.
4G has Voice over LTE which allows the use of the "data" (packet switching) network to transmit voice (similar to VoIP). However some networks and some phones don't support it and use 3G for voice.