For the first one take a look at RF profiles:
https://documentation.meraki.com/MR/Radio_Settings/RF_Profileshttps://www.google.com/search?client=f...
For a second I no sure with it's a Meraki issue. Clients are able to access the internet? They are able to log in with the credentials?
Just review your network configurations. By the way if you create an SSID open, without any security Is the result the same?
I am not a Cisco Meraki employee. My suggestions are based on documentation of Meraki best practices and day-to-day experience.
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