How could I make the clients connect to 5G SSID if their wireless stations are supported 5G?

Zyxel_Kathy

The signal strength and coverage impact the station's connection. The suggestion is to make bigger power of 5GHz, and lower power of 2.4GHz.

The lower 2.4GHz power can make less 2.4GHz co-channel interference and the stations will easier to connect with APs.

Or, you can use the band select in SSID setting. When you enable the band select, the 5GHz capable stations will connect to 5GHz first.

And, the 2.4GHz only stations might be connected to AP slower because APs need to check if they are 5GHz capable stations.