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#1 2019-08-06 19:22:20

petelewis
Trusted User (TU)
From: Birmingham, UK
Registered: 2008-08-14
Posts: 128
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[Solved] Wifi network: all looks fine, but no traffic gets through

Hi folks,

I've been banging my head against this issue for a few days. I wonder if anyone can point me in the right direction (or point out what obvious thing I forgot to check...)

I am trying to connect my laptop (a Lenovo Thinkpad Carbon X1 5th Gen) to my home wifi router (a Draytek 2110). The laptop appears to connect correctly to the router, but no traffic gets through. I am using NetworkManager, with onboard Intel wifi, and hence the iwlwifi driver.

What I've observed...

I can connect to and use many other wifi routers (universities, cafes, hotels), with different forms of authentication, from this laptop. All present no issues.

I can connect to and use the router from many other devices, computers and phones, all successfully.

With this laptop, I can connect to the wireless router with a straightforward NetworkManager GUI setup. I get an IP address via DHCP, as usual. I am in the router's DHCP table, according to its web interface, where it displays my laptop's hostname and MAC correctly.

My laptop's routing table has the router's IP as the default gateway and nothing extraneous.

I have a signal strength of around 80%.

But I can not access anything: the router, the home network or the Internet. Packets just seem to disappear into a black hole, or else anything sent back is never received by the laptop. The router (or anything else, 8.8.8.8, for example) doesn't even respond to pings -- it doesn't say the host or the network are unreachable either, ping just gives silence until I Ctrl-C.

In case this was interfering, I turned wifi power management off (also tried with it on).

I have tried both with and without the IPv6 stack enabled, and I don't use IPv6 anyway.

I tried each possible wifi frequency channel on the router, as well as 802.11 b, g, n, and mixed modes. Interestingly, when I change the channel, typically a handful of pings get through and return correctly, but then silence resumes.

DNS looks correct, but then this is an issue even with IPs, so I haven't spent much time looking at that.

At this point, I have no idea what could be responsible, or how I might debug this further.

Any ideas where to look?

All the logs look totally fine - no warnings or errors (that I can see).

Thanks.

Last edited by petelewis (2019-08-29 09:14:49)


"Cared thou not, thou would have abstained." - Xyne

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#2 2019-08-06 19:55:53

ewaller
Administrator
From: Pasadena, CA
Registered: 2009-07-13
Posts: 16,774

Re: [Solved] Wifi network: all looks fine, but no traffic gets through

Sounds like you have it covered.  Is the subnet mask of the IP set correctly?   Ensure it is not /32   Probably should be /24  for a 192.x.x.x address.
How about a firewall?  Any chance you have one running and that it dropping all packets?


Nothing is too wonderful to be true, if it be consistent with the laws of nature -- Michael Faraday
Sometimes it is the people no one can imagine anything of who do the things no one can imagine. -- Alan Turing
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#3 2019-08-08 20:40:50

petelewis
Trusted User (TU)
From: Birmingham, UK
Registered: 2008-08-14
Posts: 128
Website

Re: [Solved] Wifi network: all looks fine, but no traffic gets through

Thanks, ewaller. This is what I have...

% ip route
default via 192.168.1.1 dev wlp4s0 proto dhcp metric 20600 
192.168.1.0/24 dev wlp4s0 proto kernel scope link src 192.168.1.16 metric 600 
% sudo iptables --list

Chain INPUT (policy ACCEPT)
target     prot opt source               destination         

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination         

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination  

I disabled the firewall on the router completely, while I'm debugging.

Weird, eh.


"Cared thou not, thou would have abstained." - Xyne

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#4 2019-08-08 21:05:57

seth
Member
Registered: 2012-09-03
Posts: 12,705

Re: [Solved] Wifi network: all looks fine, but no traffic gets through

when I change the channel, typically a handful of pings get through and return correctly, but then silence resumes

Stop networkmanager, ensure no other network managing services are running (systemctl list-units) and that the router dropped the lease (your NIC disappeared) try to connect with wifi-menu. Same effect?

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#5 2019-08-08 21:39:10

petelewis
Trusted User (TU)
From: Birmingham, UK
Registered: 2008-08-14
Posts: 128
Website

Re: [Solved] Wifi network: all looks fine, but no traffic gets through

seth wrote:

Stop networkmanager, ensure no other network managing services are running (systemctl list-units) and that the router dropped the lease (your NIC disappeared) try to connect with wifi-menu. Same effect?

Thanks, and yes.

% netctl status Home
● netctl@Home.service - Automatically generated profile by wifi-menu
   Loaded: loaded (/usr/lib/systemd/system/netctl@.service; enabled; vendor preset: disabled)
  Drop-In: /etc/systemd/system/netctl@Home.service.d
           └─profile.conf
   Active: active (exited) since Thu 2019-08-08 22:33:01 BST; 32s ago
     Docs: man:netctl.profile(5)
  Process: 30732 ExecStart=/usr/lib/netctl/network start Home (code=exited, status=0/SUCCESS)
 Main PID: 30732 (code=exited, status=0/SUCCESS)
   Status: "online"
    Tasks: 2 (limit: 4915)
   Memory: 2.8M
   CGroup: /system.slice/system-netctl.slice/netctl@Home.service
           ├─30744 wpa_supplicant -q -B -P /run/wpa_supplicant-wlp4s0.pid -i wlp4s0 -D nl80211,wext -c/run/netctl/wpa_supplicant-wlp4s0.c
onf
           └─30939 dhcpcd -4 -q -t 30 -L wlp4s0

Aug 08 22:33:01 eascsl03567nl dhcpcd[30824]: DUID 00:04:0c:f5:5b:4c:30:4f:11:b2:a8:5c:af:d6:ee:a6:69:8a
Aug 08 22:33:01 eascsl03567nl dhcpcd[30824]: wlp4s0: IAID 5a:4b:e8:a3
Aug 08 22:33:02 eascsl03567nl dhcpcd[30824]: wlp4s0: soliciting a DHCP lease
Aug 08 22:33:02 eascsl03567nl dhcpcd[30824]: wlp4s0: offered 192.168.1.11 from 192.168.1.1
Aug 08 22:33:06 eascsl03567nl dhcpcd[30824]: wlp4s0: probing address 192.168.1.11/24
Aug 08 22:33:11 eascsl03567nl dhcpcd[30824]: wlp4s0: leased 192.168.1.11 for 86400 seconds
Aug 08 22:33:11 eascsl03567nl dhcpcd[30824]: wlp4s0: adding route to 192.168.1.0/24
Aug 08 22:33:11 eascsl03567nl dhcpcd[30824]: wlp4s0: adding default route via 192.168.1.1
Aug 08 22:33:11 eascsl03567nl dhcpcd[30824]: forked to background, child pid 30939
Aug 08 22:33:11 eascsl03567nl network[30732]: Started network profile 'Home'

But same behaviour.


"Cared thou not, thou would have abstained." - Xyne

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#6 2019-08-09 06:14:12

seth
Member
Registered: 2012-09-03
Posts: 12,705

Re: [Solved] Wifi network: all looks fine, but no traffic gets through

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#7 2019-08-09 06:46:58

petelewis
Trusted User (TU)
From: Birmingham, UK
Registered: 2008-08-14
Posts: 128
Website

Re: [Solved] Wifi network: all looks fine, but no traffic gets through

seth wrote:

Never heard of that, so no. Unless there's a way they can get turned on automatically.

So the short-lived pings on a reconfiguration makes me think that there's some local service that might be kicking in and interfering, once it detects a connection. I have virtualbox installed, but the network service disabled for now. Similarly for nordvpn, installed but service switched off. Wondering if either of these (or anything else) have installed some kernel level stuff or modified a network config somewhere.


"Cared thou not, thou would have abstained." - Xyne

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#8 2019-08-09 10:17:35

seth
Member
Registered: 2012-09-03
Posts: 12,705

Re: [Solved] Wifi network: all looks fine, but no traffic gets through

This might sound silly but may be an oversight: did you try remove all other clients (incl. possible repeater)  from the network and/or restart the router?

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#9 2019-08-09 15:32:25

ewaller
Administrator
From: Pasadena, CA
Registered: 2009-07-13
Posts: 16,774

Re: [Solved] Wifi network: all looks fine, but no traffic gets through

Maybe the router is confused.  Have you tried rebooting it?
Can you get a detailed log from the router?  How about its routing table? (On my router I do these through a shell)

Also, as a sanity check, can you talk to the router if you run a cable from it to your wired interface?
Any chance something out there is using the IPv4 address you have been assigned?
Perhaps try deleting all of your dhcp leases and try again.
If you are using dhcpcd, try dhclinet; or vice-versa

Can you sniff packets on a third computer (tcpdump or wireshark)?  If so, what do you see?


Nothing is too wonderful to be true, if it be consistent with the laws of nature -- Michael Faraday
Sometimes it is the people no one can imagine anything of who do the things no one can imagine. -- Alan Turing
---
How to Ask Questions the Smart Way

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#10 2019-08-29 09:14:11

petelewis
Trusted User (TU)
From: Birmingham, UK
Registered: 2008-08-14
Posts: 128
Website

Re: [Solved] Wifi network: all looks fine, but no traffic gets through

Sorry for the slow response - was on vacation :-)

Thanks for all the replies. I *think* I've fixed it. To try to narrow things down, I tried connecting from an Ubuntu live image on the same laptop, and it worked straight away. So that made me think it was something specifically to do with Arch's setup.

Did a bit more digging and I realised that I had the NordVPN package installed (from the AUR). I tried disabling the service and rebooting, but that didn't make any difference, so I ruled it out. Eventually, I uninstalled the package completely and then everything worked! So, it seems that even having that package (nordvpn-bin) installed, even if the service is not enabled, was interfering. If I get time, I'll investigate more, perhaps there is some configuration it adds.

Frustrating, but fixed (except I can't use NordVPN any more). Thanks all!


"Cared thou not, thou would have abstained." - Xyne

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