Password required with an open wireless network

I have a Rb951G-2Hnd. I reset to the factory settings with the default configuration.
Port 1 is connected to the internet and I checked the connectivity with the ping utility.
In this condition the wifi is open and enabled and connecting to the wifi network there should be internet connection.
When, with a smartphone, I try to connect to the wireless network, the smartphone (IOS and Android) requires the password!
Both devices shows the network as “Open” but then ask for a password!
Does anyone have any idea ?

What version of Router OS are you running?

What happens if you change the SSID to something else (and leave the open network).

Try to rename the SSID. If the phone has used a similarly named network before, it might remember that there was a password.

Or delete it from your remembered networks.

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Solved, there was a firewall on the network that blocked dhcp requests.