Xperia 1 II loses 4G connection in Telenor Bulgaria's network

[peter_sl]

Hello,

I've been using Xperia 1 II (XQ-AT51) for about 3 months and I keep experiencing severe network issues with Bulgaria's Telenor mobile network operator. When I'm outside of urban areas, the handset shows it is connected to 4G, but when I try to use data it immediately disconnects and displays "No coverage" for a few seconds. Afterwards, it reconnects, but it only lasts until I attempt to use data again. This cycle continues infinitely, regardless of whether I'm moving or staying still. The preferred networks setting is set to 4G/3G/2G and if I change it to 3G/2G, I don't experience the problem. Other phones in the same area don't have any network issues. You can watch a screen recording of the handset's behaviour here.

And here comes the curious part: when I go to Software Info in the Service Menu (*#*#7378423#*#* > Service Info > Software Info) I see that the Current Modem Config is Telenor_Sweden.

This is totally incorrect in my opinion and probably has much to do with the network problems of the phone, because Telenor Bulgaria does not use the same set of 4G frequency bands as Telenor Sweden, which renders the handset unable to find the frequencies it expects. If I put a SIM card of another Bulgarian operator (A1, Bulsatcom) into the phone, the Current Modem Config changes to ROW_Commercial.

I'm reluctant to take this to a service center, because as I mentioned above, this happens only outside of urban areas, and will not be reproducible at all in the city where the service center is. I'd like to hear some opinions about my theory that the wrong modem configuration is causing the network issues, as well as how you think this can be corrected. I'm guessing it would need Sony to fix the software wrongly identifying Telenor Bulgaria's SIM card as Telenor Sweden one.

Thank you,

Petar

[Strampke]

Try this:

Settings -> System -> Reset options -> reset network settings.

It should reset your mobile network automatically.

Other option:

Goto your providers' website and find APN settings

Then go settings -> network & internet -> mobile network -> advanced -> access point names 

Tap on the plus and edit access point. Then the 3 dots in the upper right corner and save

After that choose your new created access point.

Other option:

Ask your provider.

Other option:

Use a friend's SIM (not telenor) and see how that behaves.

[CosmicTomato]

It seems like you need to report this to Sony support, contact them to get it sorted.

[warp0712]

Hello Peter, 

Have you been able to solve this? I'm experiencing the same network issues on Telenor's network in Bulgaria. 

[peter_sl]

Hello warp0712, 

Unfortunately I still have this problem. The service center which services this model has proven unhelpful and unwilling to cooperate so far. My device was replaced under warranty and the new one behaves exactly the same. I've noticed that when a Telenor SIM card is in the phone, a wrong modem configuration is applied and I had written a detailed post in this thread with some technical details and error logs, which was deleted very quickly without explanation. My theory is that the carrier policy is wrong and gets confused by the similar carrier names, but how do I find a knowledgeable person to explain this to? If you are interested in taking some collective steps towards resolving this, please contact me.

Cheers, 

Petar

[Strampke]

I assume other SIMs work as expected.

What's the comment of Telenor?

What is the comment of Sony support? (You went to the service center where you bought the device, didn't you?)

Do you happen to know someone with as Samsung who's on Telenor?

Can you exchange SIMs?

[peter_sl]

Hello Strampke,

I think I've already tested all possible combinations of device and SIM:

• My Telenor BG SIM + Xperia 1 II (two different units so far) -> Network problems from day 1
• My Telenor BG SIM + Any other phone -> No problems
• Friend's Telenor BG SIM + Xperia 1 II -> Network problems
• Friend's Telenor BG SIM + Any other phone -> No problems
• Non-Telenor BG SIM + Xperia 1 II -> No problems

Telenor BG claim there are no service interruptions from their side and I agree, because nobody else complains of network issues, except me and now warp0712 as well, and also these problems have been going on since summer 2020, which is highly suspicious.
Sony's official Bulgarian service center had trouble even writing down my description correctly, let alone figuring out how to solve the problem. They replaced my device under warranty thinking the motherboard was faulty, but the new unit has the same problem. So I guess I will go one more time to them, bring a very detailed document with all my findings and hope for the best.

I am also trying to contact Mr. Dimitar Maltchev, who is the National Account Manager of Sony Mobile Bulgaria, hoping that he may be able to pull some strings faster than me going through the service center procedure.

It would also be nice to know if some actual Sony Mobile employees are monitoring this community and can start doing something about this problem, because I'm pretty sure it affects all Telenor BG + Xperia 1 II's and potentially Xperia 5 II's as well, since they share the same modem.

[Strampke]

Did you test in safe mode as well?

[peter_sl]

Yes, I tested with another Telenor SIM in my phone (third bullet point in my previous post), the problem does occur.

And yes, I did test in safe mode too, the problem does occur.

[Strampke]

😞