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#1 2020-10-15 15:45:51

VDmvKcW9JamBSir5fNfehqpG
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From: Earth
Registered: 2019-12-30
Posts: 36

Laptop constantly disconnecting and reconnecting from only one router

My ISP has made me replace my existing modem/router combo unit with one provided by them. All devices in my household connect to it perfectly smoothly, except for my laptop. My laptop will see the new network, but if I connect to it, it repeatedly disconnects and reconnects. It only stays connected for about 2 seconds at a time, then disconnects for about 10 seconds, and repeats that cycle forever. Because of this, no applications can get any meaningful data transfer, so the connection is effectively useless. The laptop does not do that on any access points other than that particular one. It does not matter whether I use the internal wireless card (Intel Centrino Ultimate-N 6300) or a USB wireless card (Realtek RTL8188EUS). Restarting networkmanager does not help, and rebooting the entire computer does not help. The only way I can actually connect my laptop to that particular access point is to connect my phone and use USB tethering. However, this runs the risk of accidentally using mobile data, keeping my phone battery at 100% for hours straight, and forgetting that it's plugged in and lifting the phone by the cable, so I don't want that to be the permanent solution. (Also, in case I have to go to school physically and my laptop starts doing this on other networks, I can't tether to my phone because it is a violation of my school's policy to have a phone or any evidence of one visible, even if I'm not actively using it, punishable by confiscation, kicking out of class, and calling parents.)

I followed the wi-fi troubleshooting guide for random disconnects, the closest thing it offered to what my problem is. Unfortunately, I have eliminated all listed causes as well as I could, and the problem has not been fixed.

Cause #1: Every time it happens, I do get

[timestamp] wlp3s0: deauthenticating from <censored> by local choice (Reason: 3=DEAUTH_LEAVING)

in dmesg every time the network disconnects. However, power saving is already off, and I double checked to make sure.

Cause #2: I do not get the appropriate message in dmesg for this to be the cause.

Cause #3: I do have a wireless cutoff switch, but the disconnections are way too predictable for me to believe the switch is responsible, and only happen when connected to that particular access point. Plus, nm-applet normally tells me when the switch is turned off, and in this case it does not indicate that the switch is turned off. Just in case, I can disable it in the BIOS the next time I get a chance to reboot.

Cause #4: Unfortunately, I am not permitted by my dad to disable the router's wireless authentication for troubleshooting purposes. I don't think the router even offers mixed-mode authentication, QoS, or to disable WPS, and every other device works perfectly (including 4 other devices within a few feet of the laptop) so I don't think we are experiencing interferance. And I don't want to mess with the wi-fi frequency settings because other people need the network too and I don't want to kick them off. The wiki also says a router that's much older than the client can be a problem, but I have a router that's much newer than the client, so I don't think that's the issue.

Cause #5: I get no DMA errors.


btw I use Arch

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#2 2020-10-15 15:59:37

V1del
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Registered: 2012-10-16
Posts: 10,867

Re: Laptop constantly disconnecting and reconnecting from only one router

I've seen that happen with bugs in NM's internal dhcp client and/or MAC address randomisation throwing your connection for a spin.

So I'd suggest you look at https://wiki.archlinux.org/index.php/Ne … HCP_client and https://wiki.archlinux.org/index.php/Ne … domization

Failing those maybe post a bit more context i.e. a more complete journal of the error.

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#3 2020-10-16 00:54:41

VDmvKcW9JamBSir5fNfehqpG
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From: Earth
Registered: 2019-12-30
Posts: 36

Re: Laptop constantly disconnecting and reconnecting from only one router

Before, the cloned MAC address field was left blank. From my basic research, I concluded that if nothing is entered, it will default to "preserve", which looks like it occasionally changes the MAC, although I don't quite understand the logic. Now, I explicitly set it to "permanent" for my network, which should use the MAC address that's burned into my network card. That did not fix the problem.

The DHCP link that you gave me is quite confusing, and I don't know what to do with it. I can tell you that I have several dhcpcd processes running on my machine, which as far as I know is not NM's internal dhcp client, so I don't think I'm using what that section refers to.

Here is my dmesg from about a minute after boot, up until right before I connected my phone to start tethering. It looks like it's just disconnect and reconnect-associated messages, with frequent spam from iwlwifi. And here are my networkmanager logs from today. Are any other logs required?


btw I use Arch

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#4 2020-10-16 05:15:33

solskog
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Registered: 2020-09-05
Posts: 247

Re: Laptop constantly disconnecting and reconnecting from only one router

VDmvKcW9JamBSir5fNfehqpG wrote:

I can tell you that I have several dhcpcd processes running on my machine,

Do you have networkmanager and dhcpd services both enabled?

$ systemctl list-unit-files --state enabled

Last edited by solskog (2020-10-16 06:06:25)

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#5 2020-10-16 06:42:03

V1del
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Registered: 2012-10-16
Posts: 10,867

Re: Laptop constantly disconnecting and reconnecting from only one router

dhcpcd is not NM's internal client and if that is actually the case that you have multiple instances of it running at the same time as NM it might very well be the reason for your issue, as stated in the note box of that section I linked there are going to be conflicts between accesses for the NIC.

And if that's the case a bit more contextual journal, not just filtered for just kernel or networkmanager, but everything that happens while NM is having the issue, based on the info so far what I'd specifically want to look out for is a dhcpcd client fighting for the network controller with NM.  I realise you seem to be quite deliberate on filtering/censoring any potentially identifiable information, but it's imperative to see a fuller picture should the suggestions so far not help.

Last edited by V1del (2020-10-16 07:36:39)

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#6 2020-10-16 14:43:22

VDmvKcW9JamBSir5fNfehqpG
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From: Earth
Registered: 2019-12-30
Posts: 36

Re: Laptop constantly disconnecting and reconnecting from only one router

I got an email about someone replying to this and pointing out that wlp3s0 is a non-standard interface name, which might be causing my issue, although I cannot find that post here for some reason. That is the default network interface name, and it has been the default on every distro I've used. Why would the default name be non-standard?

solskog wrote:
VDmvKcW9JamBSir5fNfehqpG wrote:

I can tell you that I have several dhcpcd processes running on my machine,

Do you have networkmanager and dhcpd services both enabled?

$ systemctl list-unit-files --state enabled
$ systemctl list-unit-files --state enabled
UNIT FILE                          STATE   VENDOR PRESET
autorandr.service                  enabled disabled     
cronie.service                     enabled disabled     
dhcpcd.service                     enabled disabled     
getty@.service                     enabled enabled      
lightdm.service                    enabled disabled     
lm_sensors.service                 enabled disabled     
NetworkManager-dispatcher.service  enabled disabled     
NetworkManager-wait-online.service enabled disabled     
NetworkManager.service             enabled disabled     
swapspace.service                  enabled disabled     
systemd-timesyncd.service          enabled enabled      
tlp.service                        enabled disabled     
windscribe.service                 enabled disabled     
remote-fs.target                   enabled enabled      
fstrim.timer                       enabled disabled     

15 unit files listed.

From this, it looks like dhcpcd is enabled, and none of the NetworkManager services look to me like they are NM's dhcp client, so I think NM's dhcp is disabled.

V1del wrote:

dhcpcd is not NM's internal client and if that is actually the case that you have multiple instances of it running at the same time as NM it might very well be the reason for your issue, as stated in the note box of that section I linked there are going to be conflicts between accesses for the NIC.

And if that's the case a bit more contextual journal, not just filtered for just kernel or networkmanager, but everything that happens while NM is having the issue, based on the info so far what I'd specifically want to look out for is a dhcpcd client fighting for the network controller with NM.  I realise you seem to be quite deliberate on filtering/censoring any potentially identifiable information, but it's imperative to see a fuller picture should the suggestions so far not help.

I counted and discovered that there were exactly 5 dhcpcd processes running. They all stay gone when I kill -9 them, but exactly 5 come back every time I restart dhcpcd.service. After I kill -9'ing them all, I was able to get a stable connection. My stable connection remained when I brought them back, and I was able to disconnect and reconnect with dhcpcd running. Now, I'm kinda curious what kill -9'ing dhcpcd would have done that rebooting my computer did not do. But I think that did solve my problem, so further action probably is not required.

For future reference, do I get the "a bit more contextual journal" that you wanted from just running journalctl as root with no command line options? If that's the case, the log is here if you want to look at it.


btw I use Arch

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#7 2020-10-16 18:05:50

V1del
Forum Moderator
Registered: 2012-10-16
Posts: 10,867

Re: Laptop constantly disconnecting and reconnecting from only one router

You do not want dhcpcd running in any capacity if you expect your network to be controlled by NetworkManager, that's always wrong and always has a chance to lead to conflicts.

As for wondering what it would do differently during bootup, dhcpcd is enabled so it will always try to start during boot and it will run into a fight with NetworkManager on who gets to control the device first.

Whatever dhcp client NM ends up using you won't see it in that output (... and the point of the internal client is that it's - well internal - you won't see a distinct process for it.

Decide for which of the two you intend to use and disable the other service.

Last edited by V1del (2020-10-16 18:08:48)

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#8 2020-10-17 15:31:31

VDmvKcW9JamBSir5fNfehqpG
Member
From: Earth
Registered: 2019-12-30
Posts: 36

Re: Laptop constantly disconnecting and reconnecting from only one router

Yeah, I think that might have been the problem. dhcpcd has now been disabled.


btw I use Arch

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