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

2019-04-11 22:34:46
3649 45

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.!AjSrn8DMXuPJnYsTFrtDmMDhRIC72w


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

1634342619 Author |


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

url=!AjSrn8DMXuPJnYgWyGWNhveAeD7rQQI've added three examples (modem logs and screenshots) on my OneDrive for download./url
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 but on 9.4.18 i test is ok
2019-05-06 21:12:25

Master Bunny

1634342619 Author |


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 ...

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


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

Master Bunny

1634342619 Author | from MIX 2S


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


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


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


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

Master Bunny

1634342619 Author | from MIX 2S


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

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