Login splash page not appearing! Causes, fixes?

[Gateway-SF]

Our new password-protected SSID has a Google Auth login splash page set up with block all access captive portal strength (also tried with the allow non-HTTP option enabled). Many, but not all, Mac clients are not getting a splash page to be able to login. I can't narrow down a common factor as to why they are not getting a splash page. I delete and re-add the wifi network on the Mac from the keychain and known networks; eventually the splash will appear after several attempts, but this is manual and time consuming and I'm trying to get 150 people on board. So far, the Macs are those with Intel processors and are running Monterey, and most are up-to-date with macOS 12.5.1.

Any ideas as to the cause and more importantly, a resolution?

About network:

Meraki MX250 with MS320 & 350 switches and MR42 & 52 APs. All running up-to-date "general availability" firmware.

Thank you! 🤞

[Gateway-SF]

Update here: having the captive portal set to "block all access until sign in" doesn't allow the Google login style sheet to load, and it doesn't work at all once a client enters a password - "an unknown error" appears. If captive is set to allow non-http, once the login splash does appear, it works... assuming one can get the splash page to appear to begin with.

[alemabrahao]

Hi @Gateway-SF ,

Try to create a Walled Garden and than insert these URLs:

accounts.google.com
*.googleusercontent.com
apis.google.com
*.gstatic.com
*.googleapis.com