On the laptop I name ‘Klystron’, I have kernel version ‘4.4.0-34-generic’, and the misfortune of a WiFi chip-set that uses the kernel module ‘rtl8723be’ with its companion kernel modules. Fortunately, I believe that it finally, fully stable!
I think that the most important detail on my part to getting this kernel module stable, was to add the file ‘/etc/modprobe.d/rtl8723be.conf’ to contain the following code:
options rtl8723be fwlps=0 options rtl8723be swlps=0
Yet, as a series of blog postings already shows, it was not so quick and easy to obtain stability. One reason I think that my WiFi was failing on me recently, was my persistence in trying to put the laptop to Sleep, aka “Suspend To RAM”. This was never fully supported, and after Resuming from this sort of suspend mode, the WiFi would always be unstable. The only way I had to remedy this, was to change my user-level configuration, never to put the laptop to Sleep again.
Even with the WiFi supposedly stable in this way, the malfunction remains, that for any duration of time I close the laptop lid, the WiFi temporarily cuts off, which I think is a problem with the antenna. My solution: Leave the laptop idling, with its lid open. The result: Days and days of steady connection. Some small amount of dust on the laptop keyboard.
But there seemed to have been another problem with my WiFi specifically. The modem-router which I rent from Bell seems to have a specific policy. It sets itself to be the DNS server for my LAN, which downloads the IP addresses from its DNS parent. The WiFi router seems to have a zero-tolerance policy, if any computers try to bypass it as my DNS server. And this problem can be so strict, that even to have my LAN machines act as NetBIOS / WINS server, will cause problems and stability issues, which mimic hardware WiFi disconnection issues.
In my ‘/etc/samba/smb.conf’, I needed to set
wins support = no dns proxy = yes
Otherwise, the member servers would fail to see each other as Samba-connected, and finally lose their connection altogether.
Further, I had scripted the idea into my configuration files, to prepend IP address 18.104.22.168 as an additional DNS server into ‘/etc/resolv.conf’ on boot-up, just hoping to obtain wider connectivity. But then one additional problem with that was, that this public DNS server would suggest IPv6 addresses in addition to IPv4, and that even though my user-level settings for the network said to ignore IPv6 addresses, a malfunction in the kernel – which has not bee remedied – would cause the WiFi client to try to request the IPv6 addresses anyway. My user-level settings were being ignored.
Thus, I think that getting rid of the 22.214.171.124 was instrumental in achieving stability. Since this router does not tolerate IPv6, and since it is now my only DNS server, there is no risk of IPv6 addresses ever getting mentioned on my LAN.
On that note: It is normal on a dual-stack machine, for each NIC to have an IPv4 as well as a local, “Link” IPv6 address. But I think that one aspect in which the behavior of Ethernet cards is different from WiFi, is that the Ethernet card will not try to use its IPv6 address, because that will recognize this is not a global address, which would need to be assigned by the router. It would only try to use its “link” IPv6, if it was to try to connect directly to another machine on my LAN. OTOH, It would seem that a WiFi chip-set will not recognize that its IPv6 is invalid, and will ask for “Global” IPv6 addresses.
This can be an embarrassment, if the router did not specify any, and if the router assumes that it is the only DNS server.