@Kevin_Z UNIFI is my ISP and my device can access the internet by connecting to C1200. My main router is a Mikrotik router. My network topology is pretty simple shown as the attached diagram.

I used C1200 as a simple wifi access point with no DHCP Server setting as shown in the picture. All DHCP task is getting from the main router. But, the c1200 cannot get time via the NTP server. Is...

You used this router as an ap or main router?