Users are connected via WIFI for access internet, there is a FW6310 as GW of users and this FW also has an access portal that is displayed to users if they want to browse on Internet, they have to pass the portal authentication in order to get internet connection, but once they are connected to the wirelles network, they tried to access to Internet but access portal is not displayed so that they can not browse.
Topology of solution for reference is attached to this case.
Even the portal is embedded in the FW, it is not going to be displayed to users if FW doesn't have connection to Internet, also DNS should be enabled on FW and DNS packets should be allowed on FW.
If users doesn't receive the access portal, should be checked if FW has Internet, also if DNS is not blocked on FW also should be checked if the IP segment of users is correctly configured on policy-auth on the FW.
For verify if the FW has Internet, from FW should be able to perform a ping towards Internet.
For verify that DNS is not being blocked should be checked security-policy on FW and try with "default action permit" in order to test if FW is blocking.
For verify that IP segment of users is correct on auth-policy, go to the auth-policy section on FW and check the rules and actions configured.