IAM Authentication policy - Captive portal only works with PC, not mobile phone

I have setup an authentication policy where user will re-directed to captive portal when connecting to wifi. May i know why the captive portal only works when connecting with PC, but not mobile phone. The mobile phone also failed to obtain ip address.

I think your issue is that mobile devices especially apple doesn't or can't obtain DNS. So if DNS is not present on the mobile device, it can't resolve the captive portal address.

Solution: Manually configure DNS on the mobile devices.

Captive Portal work with Android and IOS.

you may goto wifi connect screen on android or IOS

Android:
Connect SSID, it will connect showing no internet, than click on screen where the message shows it
it will re-directed to captive portal screen

ON IOS do the same as per the screen, it will work,

Have done the setup accordingly.

Network settings for Chrome OS devices are configured correctly

There are 2 option for this one by selecting "Redirect HTTPS request tocaptive portal if user is not authenticated" (please see picture 2) and other option is by "Authentication Controller"

Configuration by "Authentication Controller"
By configuring the "Authentication Controller". Portal Controller can return the MAC address of the mobile phone to IAM then the authentication page can be pushed-in

To add third party controller, goto Users” → “Authentication” → “Internet Portal Server. Then click add "Third Party Controller" (please see picture 1 for reference)

You may refer on these basic solutions for the captive portal to work on your mobile phone:
-Forget Wi-Fi connection
-Clear the Android data and cache from your device
-Reset your device to factory settings

There is no issue with the captive portal for IOS and Android mobile phone. The issue is your mobile phone is that cannot obtain an IP address. If it cannot obtain an IP address it cannot redirect to captive portal  and even in the internet.

Maybe the issue is in your mobile phone. Try to reset network settings of the mobile phone then try to reconnect again to the WI-FI.

You can enable this option, "Open auth for data flow from WAN to LAN interface".