Multiple hidden SSIDs being transmitted
Since the latest firmware update my WiFi got really bad (3.1.2). Tried to discover the cause and found out multiple SSIDs that seems to be transmitted from my router even though I only have a single active SSID.
The router WiFi MACs:
2.4GHz -> f0:9f:c2:a1:e6:34
5GHz -> f0:9f:c2:a2:e6:34
The unexpected MACs transmitting with same power in the same channels:
Factory reset didn't solved the issue.
Rolled back to 3.1.2rc2, didn't solved.
Updated to 3.1.2 again, didn't solved.
Enabled the guest network, didn't solved.
Changed the guest network to WPA2 instead of letting the default value, assigned a password, enabled and disabled the guest network. All of the hidden SSIDs disappared, except for f6:9f:c2:a1:e6:34, on the 2.4GHz channel.
Update: they come back after a while. Changing the guest network password only fixes temporarily.