We bought a new WiFi router / ADSL modem at home (Asus DSL-N55U-B) and the wifi connection occasionally has very high latencies (up to 20 seconds, versus most common 25 miliseconds when pinging google (simple
ping google.com on linux) ).
This shows up on many different devices (Windows, Linux, Android, iOS), so it's probably not a problem on the end device.
First thing I did was to check cpu load on the router, but it stays around 3% all the time. I checked used wifi channels, and tried to move our channel further from others used in our neighborhood, but this didn't help. Last thing I tried was looking at our channel with kismet and noticed that there is fairly large retry rate about half of packet rate. I'm not sure what this means exactly, but it seems suspicious to me.
The router is running linux and I have root access, so I'm not too limited in diagnostics I can run on it.
Do you have any pointers where should I continue to fix this?
So I got a new router (D-Link this time) and it's working just fine. The problem I faced with the previous router remains a mystery :-) Thanks to all for the answers.