How does automatic Wi-Fi channel selection work?

wi-fi

#1

Surf SOHO HW2 had great WiFi speeds on firmware 7.0.3 and bad speed on 7.1. Ethernet was fine. WiFi uploads were fine, but are very slow to begin with. I had noticed the slow speed on 7.1 and then rebooted into 7.0.3 to make detailed tests with many devices. Then, I rebooted back to 7.1 and re-tested all those devices and even checked they had similar signal strengths. It seemed to be consistent that 7.0.3 was fast and 7.1 was slow. I will spare you the specific details.

But then after rebooting back to 7.0.3, one device was slow again despite an excellent signal strength. Finally, I though about Wi-Fi channels. I was only testing the 2.4Ghz band and it is very crowded with many WiFi networks in the area. The router was picking the Wi-Fi channel, not me. I had also limited it to pick only channels 1, 6 or 11.

When 7.0.3 performed poorly, it had clearly picked a congested WiFi channel. I know this from the excellent WiFiInfoView program for Windows by Nir Sofer which offers tons of techie details. Changing the router to a less used channel made a huge difference in WiFi download speed.

But, I had slow speeds on 7.1 for a couple weeks before I bothered with detailed testing. So, my question.

When the router is automatically picking a channel how often does it re-evaluate it choice?

And, FYI, the logic for picking a channel seems flawed. The attached screen shot of WiFiInfoView shows the Surf SOHO at the top (two SSIDs so its the top 2 lines) using channel 11 which was slow. Forcing it channel 1 sped things up. The display is sorted by average signal strength. The fourth column is Channel Utilization, which Peplink does not report.


#2

We encounter slow speed in v7.1.0. I provided the special firmware below. I suggest try it first then only look into the issue of Wifi interference.


#3

OK, the firmware is installed and WiFi is fast again.

One example: a new Windows 10 laptop with a strong signal (-40 signal strength according to the router) tested at 63mbps down on a 100Mbps connection. Amazingly fast for 2.4Ghz in a crowded Wifi neighborhood with standard 20Mhz wide channels. Tested with speedtest.net. Same computer tested at around 6Mpbs down before.

What is different about this firmware?
Should I try forcing it to a more crowded WiFi channel for comparison?


#4

There is a Wifi related bug in v7.1.0 which fixed in this special firmware. Please try to avoid the interfered channel.