Topic: Sometimes Wi-Fi devices can't reach internet

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Post #1

alexeys

29 Oct 2016, 14:29

Hi, I have wrt1200ac running OpenWrt Chaos Calmer 15.05.1 and I'm experiencing very strange issue. Oftentimes, when a laptop connects over wifi, I can reach router but not the internet. If that happens, I need to disconnect / reconnect to wifi or sometimes even reboot the router before laptop can reach the internet. This issue is affecting several laptops in my house so I don't think it's a device issue. Any help or suggestions will be appreciated.

Here's example of pings as I connect & disconnect my Macbook from SSID. You can see that 2 pings passed successfully and then pings stop. Meanwhile, pings to my router work just fine. It seems as almost something causes router to stop routing traffic.

icmp_seq 133 (in pings to 8.8.8.8) and icmp_seq 214 (in pings to 192.168.1.1) should line up.

Request timeout for icmp_seq 133
ping: sendto: No route to host
Request timeout for icmp_seq 134
ping: sendto: No route to host
Request timeout for icmp_seq 135
ping: sendto: No route to host
Request timeout for icmp_seq 136
Request timeout for icmp_seq 137
64 bytes from 8.8.8.8: icmp_seq=138 ttl=57 time=123.969 ms
64 bytes from 8.8.8.8: icmp_seq=139 ttl=57 time=159.101 ms
Request timeout for icmp_seq 140
Request timeout for icmp_seq 141
Request timeout for icmp_seq 142
Request timeout for icmp_seq 143
Request timeout for icmp_seq 144
Request timeout for icmp_seq 145
Request timeout for icmp_seq 146
Request timeout for icmp_seq 147
Request timeout for icmp_seq 148
Request timeout for icmp_seq 149
ping: sendto: No route to host
Request timeout for icmp_seq 150
ping: sendto: No route to host
Request timeout for icmp_seq 151
ping: sendto: No route to host
Request timeout for icmp_seq 152
ping: sendto: No route to host
Request timeout for icmp_seq 153
ping: sendto: No route to host
Request timeout for icmp_seq 154
Request timeout for icmp_seq 155
64 bytes from 8.8.8.8: icmp_seq=156 ttl=57 time=16.332 ms
64 bytes from 8.8.8.8: icmp_seq=157 ttl=57 time=16.286 ms
64 bytes from 8.8.8.8: icmp_seq=158 ttl=57 time=18.590 ms
64 bytes from 8.8.8.8: icmp_seq=159 ttl=57 time=14.273 ms
64 bytes from 8.8.8.8: icmp_seq=160 ttl=57 time=96.581 ms
64 bytes from 8.8.8.8: icmp_seq=161 ttl=57 time=57.873 ms
64 bytes from 8.8.8.8: icmp_seq=162 ttl=57 time=18.254 ms
64 bytes from 8.8.8.8: icmp_seq=163 ttl=57 time=15.712 ms
64 bytes from 8.8.8.8: icmp_seq=164 ttl=57 time=11.780 ms
64 bytes from 8.8.8.8: icmp_seq=165 ttl=57 time=13.777 ms

Request timeout for icmp_seq 214
ping: sendto: No route to host
Request timeout for icmp_seq 215
ping: sendto: No route to host
Request timeout for icmp_seq 216
ping: sendto: No route to host
Request timeout for icmp_seq 217
Request timeout for icmp_seq 218
64 bytes from 192.168.1.1: icmp_seq=219 ttl=64 time=0.930 ms
64 bytes from 192.168.1.1: icmp_seq=220 ttl=64 time=55.222 ms
Request timeout for icmp_seq 221
Request timeout for icmp_seq 222
Request timeout for icmp_seq 223
64 bytes from 192.168.1.1: icmp_seq=224 ttl=64 time=1.410 ms
64 bytes from 192.168.1.1: icmp_seq=188 ttl=64 time=37177.862 ms
Request timeout for icmp_seq 226
64 bytes from 192.168.1.1: icmp_seq=227 ttl=64 time=1.583 ms
64 bytes from 192.168.1.1: icmp_seq=228 ttl=64 time=1.635 ms
64 bytes from 192.168.1.1: icmp_seq=229 ttl=64 time=104.115 ms
64 bytes from 192.168.1.1: icmp_seq=230 ttl=64 time=130.623 ms
64 bytes from 192.168.1.1: icmp_seq=231 ttl=64 time=130.364 ms
ping: sendto: No route to host
ping: sendto: No route to host
Request timeout for icmp_seq 232
ping: sendto: No route to host
Request timeout for icmp_seq 233
ping: sendto: No route to host
Request timeout for icmp_seq 234
ping: sendto: No route to host
Request timeout for icmp_seq 235
Request timeout for icmp_seq 236
64 bytes from 192.168.1.1: icmp_seq=237 ttl=64 time=1.471 ms
64 bytes from 192.168.1.1: icmp_seq=238 ttl=64 time=1.921 ms
64 bytes from 192.168.1.1: icmp_seq=239 ttl=64 time=2.267 ms
64 bytes from 192.168.1.1: icmp_seq=240 ttl=64 time=46.027 ms
64 bytes from 192.168.1.1: icmp_seq=241 ttl=64 time=125.782 ms
64 bytes from 192.168.1.1: icmp_seq=242 ttl=64 time=87.588 ms
64 bytes from 192.168.1.1: icmp_seq=243 ttl=64 time=45.082 ms
64 bytes from 192.168.1.1: icmp_seq=244 ttl=64 time=1.582 ms
64 bytes from 192.168.1.1: icmp_seq=245 ttl=64 time=1.320 ms

Post #2

bolvan

29 Oct 2016, 15:36

Both logs demonstrate bad connection and packet loss. Have you checked signal strength ?
iwinfo wlan0 assoclist

Post #3

alexeys

30 Oct 2016, 00:12

I don't have "iwinfo". How can I get it installed?

But I don't think it was signal strength. I was close to the router at that time. I had wifi disconnected, then I got connected to wifi, 2 pings went through for 8.8.8.8 and then pings stopped, for 192.168.1.1 I got few pings, few timeouts, then pings resumed. Since 8.8.8.8 won't ping, I had to disconnect from wifi again. That's when timeouts started. I connected again and both pings started running as expected so I stopped them. If I wouldn't disconnect wifi when 8.8.8.8 won't ping, I'd keep on getting sold pings for 192.168.1.1.

I'll try capturing more pings once problem presents itself again. Today it's been working fine again.

Post #4

bolvan

30 Oct 2016, 07:57

Have you checked if your neighbors use the same channel ?
They can be heavy downloading something and noise the air.
Also if you're on HT40 mode move to HT20

Post #5

alexeys

1 Nov 2016, 06:02

Looks like it's routing issue with Comcast. Although very strange because I never seen this happening before installing OpenWrt. I ran traceroute when 8.8.8.8 won't ping and trace goes outside of my local network. Is it possible that this is a NAT issue?

traceroute to 8.8.8.8 (8.8.8.8), 64 hops max, 52 byte packets
1 openwrt (192.168.1.1) 2.583 ms 0.971 ms 1.386 ms
2 96.120.90.49 (96.120.90.49) 37.277 ms 38.351 ms 39.849 ms
3 te-0-7-0-16-sur04.oakland.ca.sfba.comcast.net (68.86.142.141) 39.783 ms 39.795 ms 39.848 ms
4 be-314-ar01.hayward.ca.sfba.comcast.net (162.151.79.97) 40.183 ms 39.770 ms 39.799 ms
5 hu-0-0-0-1-ar01.santaclara.ca.sfba.comcast.net (68.85.57.145) 39.878 ms
hu-0-0-0-0-ar01.santaclara.ca.sfba.comcast.net (68.85.154.249) 40.234 ms
hu-0-0-0-1-ar01.santaclara.ca.sfba.comcast.net (68.85.57.145) 39.609 ms
6 * * *
7 * hu-0-13-0-0-pe02.529bryant.ca.ibone.comcast.net (68.86.86.94) 32.117 ms
hu-0-11-0-0-pe02.529bryant.ca.ibone.comcast.net (68.86.86.70) 39.854 ms
8 * * *
9 * * *
10 * * *
11 * * *
12 * * *

Here's trace taken from OpenWrt's Diagnostics interface from LuCI.

traceroute to 8.8.8.8 (8.8.8.8), 30 hops max, 38 byte packets
 1  96.120.90.49  8.950 ms
 2  68.86.142.141  9.483 ms
 3  162.151.79.97  9.065 ms
 4  68.85.57.145  11.272 ms
 5  68.86.90.93  12.904 ms
 6  68.86.86.70  11.191 ms
 7  23.30.206.102  11.731 ms
 8  108.170.242.241  11.480 ms
 9  216.239.49.99  11.028 ms
10  8.8.8.8  11.930 ms

Post #6

Exeleration-G

27 Nov 2016, 16:12

I'm having the exact same problem. Using OpenWrt Chaos Calmer 15.05 on a TP-Link Archer C20i, set up as a Dumb AP. I'm not really sure about the cause, but I have the feeling that downloading lots of data may induce this problem.

For instance, I had this problem a minute ago when updating my packages on a fresh Ubuntu install. What's really strange is that downloading the updated packages kept going on, but downloading any Internet page with Firefox failed. Of course, I could still reach my router's IP address.

Just posting this to see if there's anything common to our problems.

Post #7

dl12345

27 Nov 2016, 16:31

Exeleration-G wrote:

I'm having the exact same problem. Using OpenWrt Chaos Calmer 15.05 on a TP-Link Archer C20i, set up as a Dumb AP. I'm not really sure about the cause, but I have the feeling that downloading lots of data may induce this problem.
For instance, I had this problem a minute ago when updating my packages on a fresh Ubuntu install. What's really strange is that downloading the updated packages kept going on, but downloading any Internet page with Firefox failed. Of course, I could still reach my router's IP address.
Just posting this to see if there's anything common to our problems.

Yours sounds like a DNS related issue if existing downloads keep going

Post #8

Exeleration-G

27 Nov 2016, 16:49

dl12345 wrote:

Yours sounds like a DNS related issue if existing downloads keep going

Thanks, that may be it. I'm setting up Ubuntu to use OpenDNS's servers as static DNS servers. I will let you know if the problem still happens afterwards.

Post #9

bolvan

27 Nov 2016, 17:36

Exeleration-G wrote:

I'm not really sure about the cause, but I have the feeling that downloading lots of data may induce this problem.

If routers cpu is loaded 100% in kernel mode by heavy network activity then in non-preemptible (default) kernel all users processes hang. This results in losing wifi connectivity, dhcp, dns, luci, ssh.
One of the mandatory checks is cpu load.

Post #10

Exeleration-G

27 Nov 2016, 17:50

bolvan wrote:

If routers cpu is loaded 100% in kernel mode by heavy network activity then in non-preemptible (default) kernel all users processes hang. This results in losing wifi connectivity, dhcp, dns, luci, ssh.
One of the mandatory checks is cpu load.

Alright, now I understand the connection with the heavy downloading. Is it possible to restrict the kernel's CPU usage?

Post #11

bolvan

27 Nov 2016, 18:50

Exeleration-G wrote:

Alright, now I understand the connection with the heavy downloading. Is it possible to restrict the kernel's CPU usage?

No need to restrict. Need to change task scheduler strategy so it gives quantums to user processes. Recompile with kernel preemption.
If you cant then the only possibility is limiting bandwidth with shaper.

(Last edited by bolvan on 27 Nov 2016, 18:53)

The discussion might have continued from here.

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