Mobile data unavailable

[Cunctator]

Hello world,

my name is Luca, from Rome, Italy.
I bought a Xperia Z3 Compact in September, I found it to be an awesome device, but since the first day I got a strange behaviour on mobile networking.

Often even if the device shows a very strong signal like HSDPA+ at full strength ( 4/4 bars ) still my mobile internet connection doesn't work at all, and the only way to reenable its functionality is to turn on "airplane mode" and off again..

Because of the issue I contacted the Sony assistance service that guided me to the closest repair center, and in less than 2 weeks they gave me the device back, unfortunately with the very same issue still there, attached is the repair recepit that claims that the issue was not found at all, the translation of the note field is:

"Issue not found, software updated, touch parameters calibration ok, recharge and power consumption verified.
Data connection - Wi-Fi ok, if the issue will show again, proceed to configure internet/MSS setting.
Back cover broken, fixable out of warranty."

https://www.dropbox.com/s/7ttaixyqp1xqx59/recepit.jpg?dl=0

There was also a minor issue about strange "noisy" behaviour / hyper sensitivity of the touch screen that was actually fixed by the software update ( the Lollipop update was rolling out those 2 weeks here in Italy ).

The network issue itself is not 100% reproducible because some lucky times the issue doesn't show, but I managed to get a couple of screen recordings showing the issue, in both recordings I'm trying to access some internet service ( googling things or accessing some youtube clip ) but the browser and the YouTube client simply get stuck on loading. Note also that no "Network not available" alert is shown and that the signal icon in the top bar shows a full power HSDPA+ connection available.

https://www.dropbox.com/s/149fflg1ayxwcyk/record.1.mp4?dl=0

https://www.dropbox.com/s/yjpzwgkzbj4y29y/record.2.mp4?dl=0

For sake of completeness my carrier is TIM, with a LTE enabled plan.
The device is now configured to use 3G/2G networks only but the issue arise in 4G mode too.
Also the "stamina mode" and the "background data queue" are set but I spent various days trying the different permutations of these and other settings looking for a combination that would solve this thing, with no success.
I also already tried disabling bluetooth, again with no result.
The device has "developer options" enabled but is not rooted nor the boot loader unlocked.

I understand the people at the repair center cannot deeply investigate every single device they receive but I hope you will understand my disappointment in having a 500€ device that simply has its most powerful feature broken.

If you cold put me in the right direction to solve this issue it would be great.

Thank you very much for your attention and in advance for your help.
Luca Castoro

[Uliwooly]

@Cunctator

Try this

repair the phone with PCC > do NOT install any other app > uninstall any preloaded antivirus > double check the APN settings > then settings > about phone > status > signal strength > post the numbers here

also, how old is your SIM card? is it a nano SIM card or a trimmed SIM card?

[Cunctator]

Thank you uliwooly for ure super fast feedback I didn't expected that

I'm performing the system repair via PCC but meanwhile:

- I never installed an antivirus on this device.

- The APN settings have been triple checked for correctness with the carrier company.

- The signal strength was the first thing I checked months ago, the current reading is fluctuating between -73 and -91 dBm.

- The SIM card is as old as the phone, about 9 months, i got it for the Z3C since my previous phone used an old "full sized" SIM cards and of course is a nano SIM, not a cutted/trimmed standard SIM.

Thank you again for your help, I'll post here the system repair result as soon as possible.

[Uliwooly]

@Cunctator

Which carrier do you have (country too)? which Xperia Z3 compact variant do you have?

settings > about phone 

[Cunctator]

My carrier is Tim, an italian carrier, and my device is the D5803.

[Uliwooly]

 @Cunctator

Do you have another 4G phone to test the LTE network coverage?

[Cunctator]

Unfortunately no. I was wondering about buying a second SIM card with a different carrier to test it but I also need to buy an afforfable "emergency" device to keep my current SIM for work, so I'm delaying it as most as i can.
I did che software repair by che way, today i'll test che device behaviour and report here che results.

[Uliwooly · Accepted solution]

@Cunctator

It seems like a network issue but try to borrow a phone and/or a nano sim card and test it.

[Cunctator]

I did the software repair, following your suggestions @Uliwooly, Unfortunately after an almost whole day without noticing the bad behaviour in the evening it popped out again, i got a video of this thing too, if necessary i'll post it with the others.

Of course I hoped to fix this thing without the need to spend more money or time on it, 500€ and half a month seemed enough to me for a device that is still under warranty, I'll investigate further with an other carrier but really I expected a better support from a company like Sony.

For this i want to thank you once more for trying to be helpful as when customer care service fails, good users hopefully helps each other

[Uliwooly]

@Cunctator

I like to help as much as I can. I'm sorry that you are still experiencing the same issue, please do upload the videos to youtube and post the links.