Eliminating intermittent high ping to router with WiFi load

Question

For the past month, I've been experiencing intermittent high ping to my home router from all the computers on my WiFi network. For every ten pings or so, the ping will climb from the acceptable value of 1-3 ms to about 800 ms.

There are already similar questions on ServerFault and Superuser with some very good answers. A particular answer on Superuser noted that applying a load on the network (for example, running μTorrent), seemed to eliminate the high ping.

I tried it and found the same results. Here are ping values from PingPlotter: ping log

Note that the graph becomes flat as soon as I turn on μTorrent.

Instead of having μTorrent on all the time, I'm currently looking to create a lightweight program that can apply a load on the network. I tried compiling the Rust program provided on the Superuser answer, but I ended up getting the following error:

error: macro undefined: 'log!'
  --> rust.rs:11:7
   |
11 |       log! ("wifi_load] Error fetching {}: {}", url, err);
   |       ^^^

error: aborting due to previous error

So how can I create a program that would acheive an effect similar to turning on μTorrent? I'd like to note that I'm not a programmer and I don't necessarily need to use Rust — just need to accomplish the objective.

Thanks!

Answer 1

Once-per-second pings over mostly-idle Wi-Fi are a terrible way to look for latency problems, because you're not actually measuring what you think you're measuring. The problem is that Wi-Fi clients are usually battery-powered, and like to save power by using 802.11 Power Save mode, which turns the Wi-Fi radio off for brief periods of time (perhaps a few tenths of a second, but it adds up) when there doesn't seem to be any traffic to send or receive.

Once-per-second pings are not enough traffic to keep 802.11 Power Save mode from kicking in, so you can see longish ping times because of Power Save mode.

To test this theory, try running 20 pings per second. Not sure about Windows, but on Linux or macOS it would be this: sudo ping -i 0.05 192.168.0.1. This makes you send (and receive) two pings per 802.11 beacon interval (which is usually a tenth of a second), which is usually enough to keep Power Save from kicking in.

Running unnecessary traffic to keep Power Save mode from kicking in is pretty silly. It's like saying, "Hey, my car engine revs down to idle speeds when I'm stopped at a stoplight! Should I keep my foot on the gas to keep the engine revved up while I'm at the stoplight?" The answer is "No, letting it rev down is saving energy. It'll rev right back up again when you need it!"