Connection Timeouts
If an unauthenticated client reports a connection timeout error in their browser instead of receiving the splash page when fetching a website, it is likely that the Captive Portal Strength is set to “Block all access prior to sign-on” and the client is using HTTPS when fetching the website.
When the web browser of an unauthenticated client sends an HTTP GET on TCP port 80, a Meraki node can see the request, intercept it, and respond with a redirect to the splash server. If an unauthenticated client are accesses a web page outside of the Walled Garden using HTTPS, the traffic is encrypted. Therefore the AP is unable to redirect the client successfully and the traffic will be blocked. In these instances, make sure the client accessing the web page using HTTP so they can be redirected properly.
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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