Poor wifi signal with RTL8723BE and 4.13.0-32 kernel

[Robert Adam]

When using Linux Mint 18.3 alongside with the 4.13.0-32 kernel the wifi signal is really really poor (while almost sitting on the respective router) whereas with the 4.10.0-38 it works like charm.

I had to use a configuration file for getting the wifi to work properly (/etc/modprobe.d/rtl8723be.conf: options rtl8723be fwlps=0 ips=0 ant_sel=1) but chaning the antenna from 1 to 0 did not change anything with the 4.13 kernel.

I am also running Manjaro Linux with the 4.14 kernel on my machine where the wifi is also working just fine (with antenna 0 though).

cat /proc/version_signature:
Ubuntu 4.10.0-38.42~16.04.1-generic 4.10.17

(I tried using ubuntu-bug linux but it didn't work [The report belongs to a package that is not installed.])

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is missing log files that will aid in diagnosing the problem. While running an Ubuntu kernel (not a mainline or third-party kernel) please enter the following command in a terminal window:

apport-collect 1750385

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the Ubuntu Kernel Team.

[Robert Adam (krzmbrzl)]

Added requested (log)-files

[Joseph Salisbury (jsalisbury)]

Would it be possible for you to test the latest upstream kernel? Refer to https://wiki.ubuntu.com/KernelMainlineBuilds . Please test the latest v4.16 kernel[0].

If this bug is fixed in the mainline kernel, please add the following tag 'kernel-fixed-upstream'.

If the mainline kernel does not fix this bug, please add the tag: 'kernel-bug-exists-upstream'.

Once testing of the upstream kernel is complete, please mark this bug as "Confirmed".

Thanks in advance.

[0] http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.16-rc2

[Robert Adam (krzmbrzl)]

I installed the linked kernel and the wifi still wasn't working (though with antenna 1 it didn't even find the wifi in the first place and with antenna 0 it wouldn't connect (the signal was really really bad though) so it almost seems as if the problem is even worse than with the 4.13. Though that could just be coincidence).

[Kai-Heng Feng (kaihengfeng)]

Please find the first bad -rc* kernel between v4.10 to v4.13 from [1] that has this issue, thanks.

http://kernel.ubuntu.com/~kernel-ppa/mainline

[Robert Adam (krzmbrzl)]

@Kai-Heng Feng
So I went through the -rc* kernels and I found the 4.11-rc8 working just fine whereas the wifi broke down with 4.12-rc1.

[Kai-Heng Feng (kaihengfeng)]

Do you see the same issue on Bionic daily image in http://cdimage.ubuntu.com/daily-live/current/ ?

[Robert Adam (krzmbrzl)]

Do you want me to put that on a USB/CD, boot from that and check how the wifi is doing?

[Kai-Heng Feng (kaihengfeng)]

Yes. Of course a reusable media is preferable...

[Robert Adam (krzmbrzl)]

So I installed the linked image on a USB and booted that up.

The problem still persists. I also tried setting the antenna selection but it made the wifi signal even worse.

[Kai-Heng Feng (kaihengfeng)]

Do you enable Bluetooth in Manjaro? This might be yet another WiFi/BT coexist bug...

[Robert Adam (krzmbrzl)]

I have the bluetooth adapter powered off in Manjaro but I also have it powered off in Mint (I did not check the bluetooth state in the live ubuntu-image on the USB though).

[Kai-Heng Feng (kaihengfeng)]

Please do check that, thanks!

[Robert Adam (krzmbrzl)]

I did not find the option to not even power the bluetooth adapter as I can in KDE but turning bluetooth off did not seem to change the wifi behavior.

[Kai-Heng Feng (kaihengfeng)]

Can you attach kernel config on Manjaro?

[Robert Adam (krzmbrzl)]

Unfortunately I am not able to find the configuration file in Manjaro. I looked into /usr/src/ but this folder is completely empty. I also tried locating it via find -type f -name '.config' but this only found my Linux Mint Kernel configurations.

I should add that my Manjaro installation is more or less completely broken (something screwed the windowing system and apparently some more stuff) so this might be a reason why I wasn't able to find the respective file...

[Kai-Heng Feng (kaihengfeng)]

Proably `zcat /proc/config.gz` will do.

[Robert Adam (krzmbrzl)]

Here it is

[Kai-Heng Feng (kaihengfeng)]

Interesting.
Maybe CONFIG_RTLWIFI_DEBUG=y workaround the issue? The value is not set on Ubuntu.

Can you build a kernel without setting "CONFIG_RTLWIFI_DEBUG=y" on Manjaro?

[Robert Adam (krzmbrzl)]

Ahm... I can try. Never built one before and I'm not sure how well my broken Manjaro installation will cope with that. But I can definitely try it...
Do you happen to have instructions somewhere on how to build a kernel yourself?

[Paulo (paulomsmartins6)]

This Problem persist at kernel 4.13.0.32 i report the same problem in all kernels
4.13.0.36 - Bug Report #1751622
4.13.0.37 - Bug Report #1757548

Afect too TP-Link TL-WN822N