Stabilizing my Realtek rtl8723be WiFi card under Linux.

The laptop of mine onto which I newly installed Kanotix / Spitfire, and that is named ‘Klystron’, happens to have a Realtek rtl8723be WiFi chip-set, which is known to have stability issues under Linux. I found that recently my own experience also ran into these issues.

If you feel that you are also having these issues, it is important that you first check, whether in fact you have the WiFi card in question. This can be done via an ‘lspci‘ command, or with


lsmod | grep rtl8723

I felt that I needed to apply a two-prong solution to my own problem.

The first thing which I did, was to create a file named


/etc/modprobe.d/rtl8723be.conf

The only content of which was the line


options rtl8723be fwlps=0 swlps=0

This solution may solve the problem, of the WiFi dropping the connection, after periods of idle time.

There is something to watch out for. There are some sources on the Web, which state that we should try  the configuration line


options rtl8723be fwlps=N swlps=N

The problem with this method is, that for certain uses in programming, in particular in the language C, which is used for kernel modules, a numeric value may be expected in place of a Boolean value, and if in this case the module sees an ‘N’, this value will not be equal to zero, because the ASCII code for ‘N’ is not zero, and any other value than zero is taken to be True! So to make sure that the kernel module registers False, we need to put a ‘0’.

But I found that a second issue was affecting me, which was the fact that this WiFi setup has IPv6 enabled, but that my router does not tolerate IPv6. This may have been causing my laptop to get dropped from the WiFi, even as I was downloading software. In my dhcp configuration, I have added the DNS Server 8.8.8.8, which is the free Google DNS server, in addition to the auto-detected server. But 8.8.8.8 will offer the system an IPv6 resolution of a domain name along with an IPv4 resolution, and in the case of WiFi, apparently Linux will use the IPv6, without detecting that this ability was not assigned by the Access Point.

And so I felt that I also needed to disable IPv6 system-wide on this laptop. The way to do that was to add the following lines to the file ‘/etc/sysctl.conf‘:


net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
net.ipv6.conf.lo.disable_ipv6 = 1

And then ‘sysctl -p‘. After that, I also did


update-initramfs -u

This is a very sticky issue, in which different users have reported, that some of these solutions either do or do not work for them. One reason may be, that users are in fact reporting different issues without knowing it. I cannot be sure that this solution will remain 100% effective for myself, let alone for the reader. I just wanted to share my own experience with this. So far, my WiFi chipset is stable again.

(Edit 04/12/2016 : ) Just to prove to you, how uncertain the state of that WiFi chip-set is, even though I did change the parameters fed into this kernel module, it still happens that when I leave that laptop idling overnight, its WiFi goes into suspend mode. This happens in a way which the applications usually do not see, so that those applications still think they’re connected. However, my ‘Pidgin’ IRC Client gets disconnected.

And then, when I resume my session, ‘Pidgin’, which uses a ping timeout, did realize it was disconnected, and just reconnects seamlessly. And this latter part seems to happen, directly after I unlock my screen-saver, which seems to suggest that this is not being introduced by the Kernel Module, but rather by KDE, etc. I suppose it might introduce some level of confusion into the software, if the Kernel Module was to provide the same function again.

So who knows, which of my problems – if any – I may really have fixed?

Just checking my package manager, I see that ‘Pidgin’ has an available ‘Away-On-Lock’ plugin, which was not installed. Just this evening I installed and activated that, just to see whether I can override a behavior, which might have been set erroneously to ‘Offline-On-Lock’, while the plugin was not installed… By tomorrow, I should know.

Dirk

 

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