I had a similar problem.
You may need to change the regulatory domain for your WiFi to AU (or whatever is appropriate for your region/settings). With the default settings, you can’t use certain channels (11,12,13 if I understand correctly).
So, SSH to your Volumio then;
sudo iw reg get
[/code] (gets the current regulatory domain, you should see something like “country 00: DFS-UNSET”)
sudo iw reg set AU
[/code] (sets the current regulatory domain to Australia)
If you go back to the Volumio network configuration page, you should now be able to see your SSID.
To make the change permanent, go back to your SSH session;
>sudo nano /etc/default/crda
the region should have no value, change this to AU. Write file and save. Reboot to make sure you can still connect to your SSID. If not, go back and check your settings with “iw reg get”
It would be nice to have a config item on the network settings page to be able to change this.
Hope this helps.