How does automatic Wi-Fi channel selection work?



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.


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.


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 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?


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