A certain site S7500 switch portal authentication fails to pop up the authentication page

Core bypass authentication server connected to portal authentication terminals

After configuring portal authentication, the terminal fails to display the authentication interface

Check portal server status normal

 <1>dis portal server

Portal server: imc

  Type                  : IMC

  IP                    : 172.100.X.X

  VPN instance          : Not configured

  Port                  : 50100

  Server detection      : Not configured

  User synchronization  : Not configured

  Status                : Up

Debug portal shows the following error

*Jan  9 23:31:33:219 2025 1 PORTAL/7/RULE: -Chassis=2-Slot=1;

 [Inbound] execute full rule match, { MatchRes = [Rule4-Deny] }

 L3 Interface = Vlan224, L2 Interface = BAGG9, VLAN = 224, SrcMac = 82b1-7406-XXXX,

 SrcIP = 10.225.X.X, DstIP = 10.225.X.X

*Jan  9 23:31:39:206 2025 1 PORTAL/7/ERROR: -Chassis=2-Slot=1; Failed to get the host name for free rule.

Check configuration found that only the address to the portal server was allowed, need to also allow DNS port

 portal free-rule 1 source ip any destination ip 172.100.X.X 255.255.255.255

Add the following command test passed

portal free-rule 1 destination ip any udp 53

portal free-rule 2 destination ip any tcp 53 //Allow DNS query UDP OR TCP port 53

portal free-rule 3 destination ip any tcp 5223 //Special case for iOS iPhone DNS query method

The following command test is normal

portal free-rule 1 destination ip any udp 53

portal free-rule 2 destination ip any tcp 53 //Allow DNS query UDP OR TCP port 53

portal free-rule 3 destination ip any tcp 5223 //Special case DNS query method for iOS iPhone