When the main AC is down, the client still needs to perform portal authentication after switching to the backup AC

null

(1) During the portal hot backup process, after the primary AC is down and the client switches to the backup AC, portal authentication is still required.

 (2) Check whether the client's IP address has changed. If it is changed, the portal hot backup will fail.

The portal hot backup is the client's MAC+IP, which must be the same.  

Through some means, ensure that the client's IP address remains unchanged, for example: configure dhcp server to bind the IP.  

1.     Enter system view.

system-view

2.     Enter DHCP address pool view.

dhcp server ip-pool pool-name

3.     Configure a static binding.

static-bind ip-address ip-address [ mask-length | mask mask ] { client-identifier client-identifier | hardware-address hardware-address [ ethernet | token-ring ] }

By default, no static binding is configured.

One IP address can be bound to only one client MAC or client ID. You cannot modify bindings that have been created. To change the binding for a DHCP client, you must delete the existing binding first.