When a Wireless LAN Controller (WLC) SSO is set up between two WLCs in a service provider network, and there is a failover, the secondary WLC should ideally support the same client count as the primary. If only about half of the original client count is showing on the secondary WLC post-failover, it suggests that the WLCs had not completed the database synchronization before the primary WLC failed. This incomplete sync would result in a loss of client information, leading to a reduced client count on the secondary WLC.