They will operate with their last good config, but its impossible to know the exact reason with just knowing they are offline.
Likely multiple somethings in this document are not working: https://documentation.meraki.com/General_Administration/Other_Topics/Upstream_Firewall_Rules_for_Clo...
Could be vlan issues, could be firewall issues, could be routing. May be helpful to hook a laptop into the port the AP is using and seeing if you get dhcp and can get online and get to the internet in general. You may also be able to download logs from the local status page and provide them to Meraki support
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