Wifi latency issues when under load
Posted: Fri Dec 09, 2011 8:54 pm
I've been getting issues with high latency to the 7800n via wifi while the bandwidth is more fully utilised. Normally pings to the router are 0-4ms, but even when a limit is set on a connection via QoS and bandwidth usage is only reporting ~400KB/s down 70KB/s up (Adsl real tested performance max at ~2MB/s down, ~150KB/s up), pings to the router fluctuate between 100-2000ms. This even happens with under 300 connections (Checked via telnet in ip_conntrack log), but more often around
1000 connections when it's happening.
Pings from the router itself report expected latency (~20ms to google), while from my pc they report roughly the same as to the router + ~20ms, which would indicate it's only a latency issue to the actual router.
I get a strong signal to the router itself, usually max bars on windows wifi indicator(-57 RSSI in inssider) and it happens on other computers as well, so it's not the specific wifi connection.
Further more, while there is high latency to the router, the http interface is slow and sometimes returns a 400 bad request which would indicate it's something going wrong on the router (Telnet just becomes unresponsive). This is something which has barely been mentioned on the internet and I'm not sure if it's an issue with the router or just a common thing.
With a single stream downloading at near full speed (e.g. directX from Microsoft.com, at >1800KB/s) the pings to google from my pc, router and pings to router from pc only fluctuate by less than 10 milliseconds on average, so that seems fine. However, it fluctuates much more when many connections (e.g. Torrents).
I'm not 100% sure under which circumstances the high latency occurs, since it's a bit hard to tell at times. There's no warnings or errors coming up in the logs. Normal performance is fine with the exception of a few single high latency spikes (Again, to the router, not WAN).
Here's the setup I'm using:
Windows 7 (Although others running on Vista, Xp, Mac OS, iOS, Android, and Wii's)
The router is placed in a well ventilated area away at least 2m from electrical devices.
There's usually 4 devices connected to it via wifi (but anything up to 9 at the same time), mostly using 802.11g, but I'm using 802.11n
Firmware: 1.06d
Wan: ADSL2+ (Syncing at 19Mb down/1.3Mb up)
Wifi mode: 802.11b + g + n
Wifi Tx Power Level: 100
Wifi security: WPA2-PSK + AES
Ipv6: All disabled
Other than that, everything has a basic setup. (I can get further info if needed)
Firstly, I'm not entirely sure about in-depth details about wifi, but I would have thought latency to the router wouldn't significantly be effected by on partial usage of Wan connection, especially considering ~19Mb/s vs 54-300Mb/s and even when QoS actively limiting.
Does anyone have any information that could help with this? Or (besides limiting connections from the actual devices, which I've asked people to do already) what can be done about it?
Also, does the QoS prioritisation actually work? From tests, it seems to make no noticeable difference regardless of how it's setup.
-Thanks
1000 connections when it's happening.
Pings from the router itself report expected latency (~20ms to google), while from my pc they report roughly the same as to the router + ~20ms, which would indicate it's only a latency issue to the actual router.
I get a strong signal to the router itself, usually max bars on windows wifi indicator(-57 RSSI in inssider) and it happens on other computers as well, so it's not the specific wifi connection.
Further more, while there is high latency to the router, the http interface is slow and sometimes returns a 400 bad request which would indicate it's something going wrong on the router (Telnet just becomes unresponsive). This is something which has barely been mentioned on the internet and I'm not sure if it's an issue with the router or just a common thing.
With a single stream downloading at near full speed (e.g. directX from Microsoft.com, at >1800KB/s) the pings to google from my pc, router and pings to router from pc only fluctuate by less than 10 milliseconds on average, so that seems fine. However, it fluctuates much more when many connections (e.g. Torrents).
I'm not 100% sure under which circumstances the high latency occurs, since it's a bit hard to tell at times. There's no warnings or errors coming up in the logs. Normal performance is fine with the exception of a few single high latency spikes (Again, to the router, not WAN).
Here's the setup I'm using:
Windows 7 (Although others running on Vista, Xp, Mac OS, iOS, Android, and Wii's)
The router is placed in a well ventilated area away at least 2m from electrical devices.
There's usually 4 devices connected to it via wifi (but anything up to 9 at the same time), mostly using 802.11g, but I'm using 802.11n
Firmware: 1.06d
Wan: ADSL2+ (Syncing at 19Mb down/1.3Mb up)
Wifi mode: 802.11b + g + n
Wifi Tx Power Level: 100
Wifi security: WPA2-PSK + AES
Ipv6: All disabled
Other than that, everything has a basic setup. (I can get further info if needed)
Firstly, I'm not entirely sure about in-depth details about wifi, but I would have thought latency to the router wouldn't significantly be effected by on partial usage of Wan connection, especially considering ~19Mb/s vs 54-300Mb/s and even when QoS actively limiting.
Does anyone have any information that could help with this? Or (besides limiting connections from the actual devices, which I've asked people to do already) what can be done about it?
Also, does the QoS prioritisation actually work? From tests, it seems to make no noticeable difference regardless of how it's setup.
-Thanks