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MIUI ROM

[Bugs] 4G/LTE (re-)connectivity issues (Mi Mix 2S, M1803D5XA, 8/256GB) problem exists since January 2019

2019-04-11 22:34:46
3484 45
Hi,

I have a Mi Mix 2S, M1803D5XA, 8/256GB model, bootloader unlocked, running Global Beta ROM 9.3.28 with baseband version AT4.0c2.6-303-0325_2303_ea9c837. The network operator is Telefonica/O2, the service provider is 1&1. LTE coverage mostly B20/800Mhz in a rural area.

After losing 4G/LTE connection, my phone does not reconnect automatically with the available 4G/LTE network (B20, 800 MHz). I have to change the default preferred network settings (LTE/TD-SCDMA/UMTS) to "LTE only" or "LTE/CDMA/UMTS (auto) PRL" and only then the phone reconnects to the available 4G/LTE network immediately. Rebooting/restarting the phone also helps to reconnect. So I think I have to restart the modem to trigger a reconnect. If I just put the phone on the windowsill and wait for it to reconnect the modem sometimes seems to "freeze", the phone indicates a 4G/LTE connection (four out of five reception bars?), however, there is no internet connection. Again, rebooting/restarting the phone helps.

Also, if the phone has to switch from 4G/LTE to 3G or 2G it does not aggressively reconnect with "better" available networks. "Upgrading" the connection to a 4G/LTE network again takes quite some time.

I wonder why the default preferred network is "LTE/TD-SCDMA/UMTS" anyway because there is no TD-SCDMA network in Europe. I think it should be "LTE/CDMA/UMTS (auto) PRL", again, I don't know whether this is part of the problem or just irrelevant.

I noticed this issue mid-January-ish, I do not know whether it can be linked with the Mi Mix 2S' SAR value issue that was discovered by some French authorities around that time ...

EDIT: Same behaviour with 9.5.9

EDIT: This is the latest modem log file. Since I can reproduce the issue easily, I have also included a screen video.

https://1drv.ms/u/s!AjSrn8DMXuPJnYsTFrtDmMDhRIC72w

Thanks,
Lars


2019-04-11 22:34:46
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Master Bunny

1634342619 Author |

#1

The problem is still present with MIUI 9.4.26 (I've switched to Chinese ROM and xiaomi.eu ROM) by now ...

I've added three examples (modem logs and screenshots) on my OneDrive for download.
2019-05-06 21:06:43
2019-05-06 21:08:39
is something bad with 9.4.26 in 9.4.18 is ok?

i have notice that issue https://c.mi.com/thread-2137790-1-0.html but on 9.4.18 i test is ok
2019-05-06 21:12:25

Master Bunny

1634342619 Author |

#4

Alamos replied at 2019-05-06 15:12:25
is something bad with 9.4.26 in 9.4.18 is ok?

i have notice that issue https://c.mi.com/thread-2137 ...

I don't know. For me there is no difference between 9.3.28, 9.4.18 or 9.4.26 ... Basically my Mi MIX 2S Shows the same behaviour with both ROM versions.

Rebooting the phone helped/helps for all three ROM versions.
2019-05-06 22:46:54

Master Bunny

1634342619 Author | from MIX 2S

#5

Same behaviour this morning with 9.5.9
2019-05-15 15:10:31

Master Bunny

1634342619 Author | from MIX 2S

#6

Here are three screenshots of all the feedback I have sent via the official Feedback app. No improvement after 5 months! No interest to fix the issue. Very annoying and frustrating.
2019-05-15 15:13:26

Master Bunny

1634342619 Author | from MIX 2S

#7

No issues at all today, honestly. My Mi MIX 2S lost the network as expected when I walked from one side to the other side of our workshop, office and social buildings but when I took the phone out of my pocket, it immediately connected to the available 2G network (E) or was already connected. When leaving the buildings or staying close to a window in one of the offices it also upgraded the connection to the 4G network. So, no issues today.

By the way, Xiaomi Mi 9 and Mi 9SE are now officially available through O2 in Germany. Maybe Xiaomi now has implemented the correct network settings for the O2 network in their database/modem.img.

Well done, at last. Thank you!

2019-05-23 02:43:21

Master Bunny

1634342619 Author | from MIX 2S

#8

I stand corrected. Almost immediately after I wrote the above posts I encountered the same problems with my Mi MIX 2S. What the hell...
2019-05-23 22:25:23

Feedback Team

Sampath madurai | from Redmi Note 4

#9

Dear user
Thanks for your report, Sorry for the inconveniences I Discuss this issue with Team Member.
Thanks
2019-05-23 23:36:14

Master Bunny

1634342619 Author | from MIX 2S

#10

Sampath madurai
Dear user
Thanks for your report, Sorry for the inconveniences I Discuss this issue with Team Member.
Thanks

Thanks. Highly appreciated. Let me know if you need any further modem log files.
Thanks!
2019-05-24 00:49:41
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