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Redmi Note 9/S/Pro

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[Discussion] Redmi Note 9S!! WLAN ISSUE

2020-04-23 01:53:56

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Redmi Note 9S!! WLAN ISSUE

Brice  replied at 2020-04-23 02:34:01
Could you describe what type of wlan issues are you experiencing? Unable to connect?

When you let the device go to sleep for few hours or minutes wifi stops working. It does not lose the connetion to the wifi. It just has no more access to the internet and the device does not switch to mobile internet on it's own. You need to turn off the wifi and reconnect it again in order to gain internet access.
Same issue in both, 2,4ghz and 5ghz seperate networks or together in one SSID. Switching the wifi standards 802.11a/b/g/n/ac has also no effect. Likewise changeing the Private DNS option ore the use of a static IP in the network.

In the Mi Community are already some other threads regarding this big BUG:

Even at XDA it's a Topic: ... ps-leaving-t4085213

A german android forum also trys to find the cause: ... 6gb-128.944828.html

And even a german review is mentioning this BUG:

Most of the users have a FritzBox and they are very popular in germany. It's not an problem of the FritzBox because every other divice is working. Only the Note 9S has this problem.

The Note 9S is so far the only device available on the German/international market with a Qualcomm 720G, which makes the theory of a driver bug somehow likely. The realme 6 Pro, which also has it built in, is currently not available in markets where the Fritzbox is so strongly represented as in Germany and from this direction I haven't heard of any problems. Fritzbox is trying hard to keep all routers up to date with the latest software and the WiFi driver of the 720G might not work with certain new network standards or protocols.

2020-04-23 14:54:38
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Brice  replied at 2020-04-23 02:34:01
Could you describe what type of wlan issues are you experiencing? Unable to connect?

do you have any new informations regarding the state of the WiFi bug of the Redmi Note 9S? Slowly you can find more and more reports about this bug all around the EU. And not only with the AVM FritzBox devices. More or less every second user on Amazon Germany is writing about this Bug.
2020-04-30 21:04:06
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somtimes it reconnects after a few minutes, but the Problem ist not solved with the update. it's only a little step in the right direction


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2020-05-01 05:39:50
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Redmi Note 9S!! WLAN ISSUE

happybuddhist replied at 2020-05-01 04:40:42
Hi there!

Can someone submit a detailed bug report and share the report ID here? It seems the bug fix in this update hasn't solved for most of the users. Kindly shared the bug report so that I can push this issue to the relevant team.

Report ID: 505564639
It is a German report, so I'll just put it in a nutshell.

The note 9S loses the connection to the internet via WiFi in standby after some time (8-10 minutes), even with the new update and does not switch to mobile internet. So it is offline!
I use a Fritz!Box 7590 with Fritz!OS 7.12 and WAP2 key. An absolut standard WiFi network in germany. It doesn't matter if 2.4GHz and 5GHz are running under one SSID or are separated. All other devices in the network run without problems. I have already reset the phone once, deleted the WiFi connections several times and reconnected them.

The interesting thing is that the phone is still receiving the router's ID/MAC, but can't send anything.

I have tested it with the App "Tasker". I can trigger a ping which is only done when the phone is connected to my router's ID/MAC. So Tasker detects the connected ID/MAC without any problems while the bug occurs, but I can't find the ping on the network. This means the download is there and the packets from the router to the Note 9S are received, but no upload from the Note 9S is possible in this state. Therefore the Note 9S will be disconnected by the router, because it doesn't receive any feedback.

Means download is available, but no more upload.

The strangest thing I noticed today is that when you open an unencrypted guest WiFi with the same router, the bug does not appear.

It looks like the Note 9S will lose the network key or something similar after a while in standby.

But unfortunately I have no deeper insight into the logs of the WiFi module in Note 9S. That's where Xiaomi's support has to act now. Especially now that the next Note with the same Qualcomm 720G will be released on the global market, the bug has to be fixed first. It will be a real media disaster if a whole range of models is available on the global market with the same bug.
2020-05-01 18:38:42
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it's a sad thing that as a user i currently only have the option to fix the bug temporarily by sending a ping with Taker every few minutes and restarting the WiFi if it fails.
It is as if the phone in standby mode no longer checks itself with a ping as long as it receives packets from the network.
2020-05-01 18:55:42
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Redmi Note 9S!! WLAN ISSUE

This should be only an temporary solution. It can't be that we as user need to find a fix for sometihng that is clearly the failure of the manufacturer and even this seems to be not a proper soltuion. Some users have even with a repeater the WiFi Bug
2020-05-03 00:21:25
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Redmi Note 9S!! WLAN ISSUE

happybuddhist replied at 2020-05-01 12:41:13
Thanks for the extensive report. I have got a few user reports already and I've sent them to relevant team for checking. Hopefully we'll hear from them soon.

I have found something very interesting in my attempts today to find the problem. If the error occurs then the upload is not really broken. I can still see all other networks and can instandly reconnect me to any other network without restarting the WiFi of the phone.
Together with the facts that when you open an unencrypted guest WiFi with the same router, the bug does not appear and in some casec you can skip the bug with an repeater also I have no problem with the WPA2-PSK (AES) encrypted WiFi in my Office, there could be a trigger for the bug.
This leads me to the conclusion that the reason lies in the type of encryption. The encryption for the newer FritzBox devices is WPA2-PSK (CCMP) which is an advanced Version of WPA2-PSK (AES) and you can't change it in this devices. All the other devices, that I have found, where the bug does not appear have the WPA2-PSK (AES) encryption.
So this could be the key to solve the bug. Maybe the encryption service of the Note 9S stops working properly in StandBy after some time and the WPA2-PSK (CCMP) key can't be generated.
Can you sent this hint to relevant team?
2020-05-03 06:28:05
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KIIIMO replied at 2020-05-07 10:39:03
all FritzBox have this conflict with redmi note 9s
not sure yet if it's phone problem or router software problem.

but every other device I have/had was working without a problem with my 7590. I have even tested my old OnePlus 2 in the last few day. It had no problems and all my other devices too. I can even reconnect me manually to my second SSID of the 7590 without restarting the WiFi of the Note. It has to be a problem with the software of the Note.

It does not even notice that the internet connection of a WiFi network is down. I tested it with my router. Dialed into Wi-Fi. Disconnected the Internet on the router and there was no message that the Note wants to switch to the mobile data because the WiFi connection has no Internet access anymore. This should be the default behaviour of an Android system when this happens, but the Note does nothing in this case.
2020-05-07 16:58:08
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happybuddhist replied at 2020-05-03 02:50:49
Excellent. Thank you for the heads-up. Hope this would be useful for the team.

I may have found another good hint.

I've been asking some of the custom ROM developers here and there about the problem. Those who do not develop their ROM based on MIUI have no problems at all. Others who modify MIUI have the same problem with WiFi. The cause seems to be the management of Android by the current MIUI version.
2020-05-08 15:54:04
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KIIIMO replied at 2020-05-08 14:48:22
Snow now after so many different reviews from different countries left us only 2 reasons .
Either Software problem (Miui) and can be fixed with next miui which our phone not even listed in it which I don't know why, or hardware problem which would be really bad .

This will not be a hardware problem. Like I said the custom ROM developers who do not develop their ROM based on MIUI have no problems at all with the WiFi and in some cases the WiFi of the official global ROM works perfectly fine. Like an unencrypted WiFi......
2020-05-08 21:08:12
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