Problems with Wifi signal under Linux

Detailed problem description: On a brand new laptop (HP Notebook – 15-ba006nm, P/N: 1BV18EA, some more details) with RTL8723BE PCIe Wireless Network Adapter under a quite new version of Linux (Linux Mint 18.1) with kernel 4.4.0-92-generic I’ve noticed very poor Wifi signal reception. In a distance of 1.5 meter from a router the Wifi signal strength was reported as 48%. The connectivity was breaking often requiring manual reconnection. In another room the laptop could not receive the Wifi signal at all while 2 older laptops did it without any problems.

I was suspecting a hardware problem like broken antenna of wireless network adapter when I’ve found this article: Realtek RTL8723BE PCIe Wireless Network Adapter not working in Ubuntu 16.10

This article suggested this particular Wifi hardware (RTL8723BE) has more than one antenna and that the Linux driver is not selecting the correct one. What a surprise! Then I found a blog post ArchLinux: “rtl8723be wifi connection issues solved by antenna selection” which explains how it is possible: Wifi chip supports two antennas but hardware producer connected only one antenna.

Solution

The solution was to issue the below command and reboot the computer:

sudo tee /etc/modprobe.d/rtl8723be.conf <<< "options rtl8723be ant_sel=1"

After this operation all reported problems were gone.

PS. How to check under Linux what is the Wifi network adapter?

Use lspci command and search for a line with “wireless” word.

Update

After around half a year suddenly the problem returned. I guess it was caused by some system update (January 2018). This time the problem was solved by changing antenna selected in the above-mentioned configuration file /etc/modprobe.d/rtl8723be.conf to “2” so the file’s content became this:

options rtl8723be ant_sel=2

You can edit the file with “nano” text editor run like this:

sudo nano /etc/modprobe.d/rtl8723be.conf

Remember to reboot after editing this config file.


UPDATE 2

On the same laptop the problem stays under Ubuntu 18.04 LTS with kernel 4.15. The solution is the same, the antenna to select is “2” – so you need this command and a reboot:

sudo tee /etc/modprobe.d/rtl8723be.conf <<< "options rtl8723be ant_sel=2"

UPDATE 3 (28.08.2018)

After running software update the kernel of my Ubuntu was upgraded to version 4.15.0-33 and… Wifi signal reception dropped again (others reported this as well). This time the “ant_sel” trick didn’t work! The only hope was to follow instructions from rtlwifi_new project on GitHub. And it helped in my case. Still I need to use driver option “ant_sel=2”.

About krzysztoftomaszewski

I've got M.Sc. in software engineering. I graduated in 2005 at Institute of Computer Science, Warsaw University of Technology, Faculty of Electronics and Information Technology. I'm working on computer software design and engineering continuously since 2004.
This entry was posted in hardware, Linux. Bookmark the permalink.

3 Responses to Problems with Wifi signal under Linux

  1. The same configuration fix is need for this laptop/Wifi hardware under OpenSUSE Leap 42.3 with

  2. Upgrading to kernel 4.15.0-34 under Ubuntu was a little bit too much for me. Wifi signal reception was gone again. On GitHub page https://github.com/lwfinger/rtlwifi_new I saw information about the “rtlwifi_new” driver being not compatible with Ubuntu. So I… reverted to the kernel 4.15.0-33 using instructions from http://karlcode.owtelse.com/blog/2017/03/13/reverting-to-a-previous-kernel/
    Waiting for some kernel around version 4.19 which is supposed to fix this Wifi issue… hopefully.

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