CM5 Wi-Fi was slow on 2.4 GHz – now connecting to 5 GHz

uConsole
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Hello Everyone

Posting this in case it helps others using Raspberry Pi CM5 (in my case on uConsole).
Initially, Wi-Fi performance felt very slow, and it turned out the system was connecting to 2.4 GHz by default.

Problem

Out of the box, Wi-Fi showed:

freq: 2427

This means 2.4 GHz, which is:

  • Crowded

  • Limited in bandwidth

  • Often slow, especially in compact or metal enclosures

How I fixed it

First, I checked which band was being used:

iw dev wlan0 link

Then I forced the connection to use 5 GHz via NetworkManager:

nmcli connection show
nmcli connection modify "<connection-name>" 802-11-wireless.band a
nmcli connection up "<connection-name>"

I’m also using an external SMA antenna, installed via a Wi-Fi mod from Printables, which helped improve signal quality compared to the onboard antenna.

Result

After reconnecting, the link now shows:

freq: 5180

This confirms the CM5 is connecting to 5 GHz, and Wi-Fi performance is noticeably better and more stable.

Summary

  • CM5 may connect to 2.4 GHz by default, which feels slow

  • iw dev wlan0 link clearly shows which band is in use

  • Forcing 5 GHz and using an external SMA antenna significantly improves performance

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2

If you couldn’t bother writing your post here, and had a computer do it instead, why should anyone bother reading it?

Here’s what your post would have looked like had a human written it:

Oops, today I realized I was on 2.4GHz instead of 5GHz (which trades resiliency for bandwidth). I found out because I noticed it was slow and iw dev wlan0 link confirmed it. The trick to fixing it is nmcli connection modify "<connection-name>" 802-11-wireless.band a && nmcli connection up "<connection-name>".

Did you notice how that took 1 paragraph and a minute to read? If you don’t wanna take the time to even write that much, just post your prompt so we can go look at someone else’s program output ourselves.

3

and the most likely improvement has nothing to do with anything the thread is claiming to be about but the hidden note about switching to a different antenna instead of the pcb antenna stuck directly to the metal of the case

1 Like
4

hiyall folks

i just needed to store this somewhere.
i had the issue of Ubuntu 22.04 not connecting to my 5Ghz wifi using the onboard CM5 device even though my other devices were connecting to it just fine. even after all the hardware mods with long antennas etc, i finally figured it out.

in Ubuntu at least, power_save must be off.
after loads of testing, this is the setting that would make it work reliabily.
you can set this up by using
$ sudo iw dev wlan0 set power_save off
or by using NetworkManager

$ sudo vi /etc/NetworkManager/conf.d/wifi-powersave.conf
[connection]
wifi.powersave = 2

once that is done… things are stably connecting thereafter.
Hope this helps someone.

1 Like