@gbon 

Hi, I tested the Wi-Fi name and the password could be changed when I am still on the Wi-Fi network.

Did you log into the owner account of the Deco, not the manager?

If the client is gonna connected via LAN cables, I think it does not need to care for the Wi-Fi settings. But space seems always unrecommended as the wireless name and password since it is easily neglected.

For more details, you could also have a look at this link:

Special Characters are not suitable as Wi-Fi Name and Password

Thank you very much.

Best regards.