Ubuntu keeps booting me off of 5GHz WiFi network and prompting for password

Question

I know this is a common problem. I've searched and searched for a solution but nothing has helped me.

I have a 5GHz WiFi network that I'd rather be on because it allows me to reach higher speeds, but Ubuntu regularly boots me off the network and prompts me for the password. It's rather sporadic and inconsistent - sometimes I'll be randomly prompted for the network password, and sometimes it'll take it and reconnect me, or it'll prompt again a few seconds later, or it'll just boot me off entirely. This issue also occurs on a clean installation of Ubuntu.

Similar issues do not occur on other computers running other operating systems. I've discovered that I can delay the issue from occurring by rebooting my router, but it will only be okay for a day or two before Ubuntu starts kicking me off the network again. This issue does not occur on the 2.4GHz variant of my network. I don't recall all of the things that I've tried (and failed) to solve my issue, but I do recall disabling 802.11n in Ubuntu. Unsurprisingly, this did nothing to alleviate the problem.

I am not well-versed when it comes to using Linux and I usually don't understand how to carry out another user's instructions which is part of what made researching solutions so difficult. Can anyone help me out here? I've almost completely lost my patience with this rather ridiculous problem.

Edit: Here's the output of iwconfig (I've cut out my SSID name and replaced it with ProblematicNetwork):

lo        no wireless extensions.

enp6s0    no wireless extensions.

wlp7s0    IEEE 802.11  ESSID:"ProblematicNetwork"  
          Mode:Managed  Frequency:2.462 GHz  Access Point: FC:2B:B2:BF:0F:92   
          Bit Rate=65 Mb/s   Tx-Power=22 dBm   
          Retry short limit:7   RTS thr:off   Fragment thr:off
          Power Management:on
          Link Quality=69/70  Signal level=-41 dBm  
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:106   Missed beacon:0

And, here's the output of iwconfig, but showing the network's 5GHz ability:

lo        no wireless extensions.

enp6s0    no wireless extensions.

wlp7s0    IEEE 802.11  ESSID:"ProblematicNetwork"  
          Mode:Managed  Frequency:5.785 GHz  Access Point: FC:2B:B2:BF:0F:96   
          Bit Rate=292.6 Mb/s   Tx-Power=22 dBm   
          Retry short limit:7   RTS thr:off   Fragment thr:off
          Power Management:on
          Link Quality=61/70  Signal level=-49 dBm  
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:3  Invalid misc:79   Missed beacon:0

Answer 1

First, there are two SSIDs with the same name, ProblematicNetwork. One is the 2.4 gHz segment and the other is the 5 gHz segment of, I assume, the same router. I am quite confident that you have told Network Manager to connect automagically to ProblematicNetwork when available and that your dropping is the wireless device hopping from one instance of ProblematicNetwork to the other, always looking for a better connection, sort of like my ex-girlfriend!

I suggest that you rename one or both to prevent this. Perhaps ProblematicNetwork-2.4 and ProblematicNetwork-5.

Next, there are several things that you might tweak to make your connection even better.

First, check the settings in the router. WPA2-AES is preferred; not any WPA and WPA2 mixed mode and certainly not TKIP. Second, if your router is capable of N speeds, you may have better connectivity with a channel width of 20 MHz in the 2.4 GHz band instead of automatic 20/40 MHz, although it is likely to affect N speeds. I also have better luck with a fixed channel, either 1, 6 or 11, rather than automatic channel selection. Also, be certain the router is not set to use N speeds only; auto B, G and N is preferred. After making these changes, reboot the router.

Then set your regulatory domain explicitly. Check yours:

sudo iw reg get

If you get 00, that is a one-size-maybe-fits-all setting. Find yours here: http://en.wikipedia.org/wiki/ISO_3166-1_alpha-2 Then set it temporarily:

sudo iw reg set IS

Of course, substitute your country code if not Iceland. Set it permanently:

sudo nano /etc/default/crda

Change the last line to read:

REGDOMAIN=IS

Proofread carefully, save (Ctrl+o followed by Enter) and close (Ctrl+x) the text editor.

Any improvement?

Answer 2

I need a better understanding of your network configuration, as I suspect a channel interference problem.

How many routers do you have?

In your router(s) you can set each 2.4/5GHz network to specific channels. In 2.4GHz it might be channels 1-11 or auto. In 5GHz it might be between ~36 to ~149. That's the info I'm looking for.

Do you have Wifi Analyzer installed on your smartphone? Also show me iwlist wlp7s0 freq.

Please complete this table and enter it into your question...

Router #1   2.4GHz name   2.4GHz channel   5GHz name      5GHz channel
--------- | ----------- | -------------- | ------------ | ------------
basement                     11/auto                          140?

Router #2   2.4GHz name   2.4GHz channel   5GHz name      5GHz channel
--------- | ----------- | -------------- | ------------ | ------------
upstairs

Update #1:

The problem is that the basement router's 5 GHz network is set to a channel that's outside of the capabilities of your modem card. Note on the iwlist wlp7s0 freq command when connected to the 5 GHz network, it shows that you're connected to frequency 5.785 GHz, but the your card only goes as high as channel 140, frequency 5.7 GHz.

      Channel 140 : 5.7 GHz
      Current Frequency:5.785 GHz

You need to set the 5GHz channel to one of the highest number channels that both the router and the modem card support. It might be 140, or it might be a channel slightly lower. Higher channels work better.

You also need to assure that the upstairs router's 2.4 GHz and 5 GHz channel settings are different than the basement router's settings.

Better yet, would be to eliminate the upstairs router, move the basement router upstairs, and let it cover the entire house. Any blind spots should be fixed by adding repeaters, or by getting a newer/stronger router.

Lastly, how are you connecting two routers to one cable/DSL modem?