Invalid WiFi 2.4GHz issue with 10.2.1.0 (stable) on Mi Mix


Dec 3, 2017
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#1
Hi
after upgrading my MiMix from 10.1.1 stable to 10.2.1 the Wifi only sees/scans 5GHz WiFi networks, no longer 2.4GHz ones...
I've done an upgrade (dirty flash) over the perfectly working 10.1.1
Couldn't find this issue mentioned around here
thanks
 
Dec 2, 2017
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#7
Flashed it, no difference... The Mix still only sees access points announcing 5GHz.
Thanks for your support
Can you check which 2.4Ghz channels are available, possibly on some other phone?

Channel 13 seems to be often problematic, but 1 - 11 at least should be fine.

The only thing I could suggest would be to try flashing the latest eu weekly, it is working fine on my Mix1, which sees all channels 1 - 13.
 
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Dec 3, 2017
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#8
@cobben, you're right!
I've found the cause of the problem:
Channel 13 of 2.4GHz isn't apparently supported by this new stable ROM (while it definitely was with previous version 10.1.1)
As luck goes, my 2.4/5 GHz access point was set - hell, forced - to channel 13 for the lower band :)
As soon as I've switched to another channel, the Mix was able again to see the 2.4GHz band.
Thanks everyone for your time
 
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Dec 2, 2017
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#9
@cobben, you're right!
I've found the cause of the problem:
Channel 13 of 2.4GHz isn't apparently supported by this new stable ROM (while it definitely was with previous version 10.1.1)
As luck goes, my 2.4/5 GHz access point was set - hell, forced - to channel 13 for the lower band :)
As soon as I've switched to another channel, the Mix was able again to see the 2.4GHz band.
Thanks everyone for your time
I have a problem with my Max1 Prime, which for now cannot see Chanel 13.
It used to be able to, and on the same rom.
Have no idea what happened.

Chanel 13 is not allowed in the US, but is in Europe, so it is a little special apparently.
 
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Igor Eisberg

Patch/Mod Developer
Staff member
Oct 6, 2016
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#10
I have a problem with my Max1 Prime, which for now cannot see Chanel 13.
It used to be able to, and on the same rom.
Have no idea what happened.

Chanel 13 is not allowed in the US, but is in Europe, so it is a little special apparently.
That's why I'm surprised. We force UK/GB for WiFi region for those in the EU region, but even with region set to IT for the OP, he can't see channel 13 for some reason.
 
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Dec 2, 2017
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#12
I just tested on my Max1 helium EU 9.1.3, and it cannot see channels 12 and 13, 2.4Ghz wifi, when there is no simcard.

It can see channel 12 and 13 with a simcard, roaming or not roaming.

Everything else seems to work normally, all other channels 2.4Ghz wifi, and 5Ghz wifi.
 
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Igor Eisberg

Patch/Mod Developer
Staff member
Oct 6, 2016
1,164
903
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#13
I just tested on my Max1 helium EU 9.1.3, and it cannot see channels 12 and 13, 2.4Ghz wifi, when there is no simcard.

It can see channel 12 and 13 with a simcard, roaming or not roaming.

Everything else seems to work normally, all other channels 2.4Ghz wifi, and 5Ghz wifi.
... then you should have said so from the start.
If no SIM Card is in the device, Wi-Fi region will be set to the region set by your display language.
If you're using "English (United States)" - no channel 12 and 13 for you. If you use "English (United Kingdom)" you will see both channels.
(You need to reboot after changing language for the Wi-Fi region to take effect)
 
Dec 2, 2017
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#14
... then you should have said so from the start.
If no SIM Card is in the device, Wi-Fi region will be set to the region set by your display language.
If you're using "English (United States)" - no channel 12 and 13 for you. If you use "English (United Kingdom)" you will see both channels.
(You need to reboot after changing language for the Wi-Fi region to take effect)
I had no idea from the start that the wifi problem could be related to the SIM cards or system language.

Now that I know, it is not a problem.

Thanks for the explanation, the language discrimination is quite fascinating.

I of course as an expat American automatically choose US English over that decadent version still spoken on those dirt poor islands off the coast off Scandinavia.
 
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Igor Eisberg

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Oct 6, 2016
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#15
I had no idea from the start that the wifi problem could be related to the SIM cards or system language.

Now that I know, it is not a problem.

Thanks for the explanation, the language discrimination is quite fascinating.

I of course as an expat American automatically choose US English over that decadent version still spoken on those dirt poor islands off the coast off Scandinavia.
In official ROM, if you don't put a SIM in, the Wi-Fi region is set to nothing, and then you will not see 5GHz networks at all, and that was a serious issue for Mi Pad 4 (Wi-Fi only) users.
Wi-Fi has different regulations. How do you think the appropriate regulation is being set? By your SIM card region.
We extended this to default to system language region in case there is no SIM inside, to allow using 5GHz.
 
Dec 3, 2017
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#17
Ouch, that applies to me as well.
I'd never have thought of any possible relationship between English US (my default language choice for devices) and SIM card - or lack thereof - and WiFi channels.
But now that you've mentioned, it makes sense. It really does.
And me thinking my only mistake was forcing the access point to channel 13... Lol.
Live, and learn.
... then you should have said so from the start.
If no SIM Card is in the device, Wi-Fi region will be set to the region set by your display language.
If you're using "English (United States)" - no channel 12 and 13 for you. If you use "English (United Kingdom)" you will see both channels.
(You need to reboot after changing language for the Wi-Fi region to take effect)
 
Dec 3, 2017
31
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#18
(...)I of course as an expat American automatically choose US English over that decadent version still spoken on those dirt poor islands off the coast off Scandinavia.

Now you've got me thinking.. why on earth do I choose US English as the system language for all my devices...
 
Dec 3, 2017
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#19
Thanks, great explanation!
In official ROM, if you don't put a SIM in, the Wi-Fi region is set to nothing, and then you will not see 5GHz networks at all, and that was a serious issue for Mi Pad 4 (Wi-Fi only) users.
Wi-Fi has different regulations. How do you think the appropriate regulation is being set? By your SIM card region.
We extended this to default to system language region in case there is no SIM inside, to allow using 5GHz.
 
Dec 2, 2017
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#20
Now you've got me thinking.. why on earth do I choose US English as the system language for all my devices...
Well, I was just joking, and poking my Brittish "The King's English" cousins in the ribs a little.

There used to be very good reasons why you should always choose US English as your system language - if you didn't, nothing would work!

Actually, there are still quite a few problems like that popping up now and then, also here on Xiaomi.EU - messed up translations that stop things from working.

This is the first time I can recall where having US English as system language caused a problem.
It's still mostly the other way around.

Now you can even choose Russian or Swedish in Google Maps (for spoken navigation directions), it used to be I had to switch system language to Russian or Swedish to get that.
 
Dec 3, 2017
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#21
I was just kidding, of course :)
US English has always been my choice for operating systems since well before phones got 'smart', but this is the first time ever that choice backfired.. Time to switch to native language perhaps. Not.
 
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Dec 2, 2017
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#22
In official ROM, if you don't put a SIM in, the Wi-Fi region is set to nothing, and then you will not see 5GHz networks at all, and that was a serious issue for Mi Pad 4 (Wi-Fi only) users.
Wi-Fi has different regulations. How do you think the appropriate regulation is being set? By your SIM card region.
We extended this to default to system language region in case there is no SIM insideGhz , to allow using 5GHz.
I just tried changing the system language in my Max1 hellium EU 9.1.3, which is now without simcards again.

It could not see channel 13 of 2.4Ghz wifi with any of English UK, svenska, русский as system language, with a reboot each time.

This bug has near 0 priority for me personally, just though you should know.

It will likely cause sporadic bug reports from others, just like this thread.
 
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Dec 2, 2017
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#24
Do a logcat while switching Wi-Fi on and off multiple times.
Code:
adb logcat -s wpa_supplicant
I'll have to wait to tonight to do the ADB thing.

I just did an experiment on my Mi Note 2 scorpio running EU 9.1.17.
System language US English, wifi region 'GB' .

I turned off "Mobile radio power" with a toggle in the app NetMonster, without removing
the simcard.

After then toggling wifi off and on again, channel 13 disappeared.

When I turned on "Mobile radio power" again, and toggled wifi off and on again, channel 13 reappeared.
No rebooting was necessary.

Addendum:

I changed system language to UK English and tried the same experiment, and channel 13 never disappeared.
No reboot necessary.

This is how it should work, with the current implementation, yes?

So this bug seems limited to the Max1.

Adendum2:

Same result on the Mix1 lithium as on the Note 2 - switching to UK English keeps channel 13 available with "no simcard".

Will try the Max1 tonight.
 
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Igor Eisberg

Patch/Mod Developer
Staff member
Oct 6, 2016
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#25
I'll have to wait to tonight to do the ADB thing.

I just did an experiment on my Mi Note 2 scorpio running EU 9.1.17.
System language US English, wifi region 'GB' .

I turned off "Mobile radio power" with a toggle in the app NetMonster, without removing
the simcard.

After then toggling wifi off and on again, channel 13 disappeared.

When I turned on "Mobile radio power" again, and toggled wifi off and on again, channel 13 reappeared.
No rebooting was necessary.

Addendum:

I changed system language to UK English and tried the same experiment, and channel 13 never disappeared.
No reboot necessary.

This is how it should work, with the current implementation, yes?

So this bug seems limited to the Max1.

Adendum2:

Same result on the Mix1 lithium as on the Note 2 - switching to UK English keeps channel 13 available with "no simcard".

Will try the Max1 tonight.
Yes, this is how I designed it to work, and sounds like Mi Max (which is Android 7.0) is having difficulty behaving like Mi MIX and Mi Note 2 (both Android 8.0).
And sure, rebooting is not mandatory if you remove the SIM or just simulate a SIM removal. The key here is to make the radio update the Wi-Fi region internally.