NTP doesn't switch to the other node automatically

Dears,

I have configured two NTP servers on the chrony.conf file. I have blocked the first NTP server from the firewall. However, the NTP switching was not happen. I have waited for for 10 minutes, and since the shift was not done automatically I have restarted the chronyd service. Then the NTP was switched to the second NTP server.

Hint: The blocking was done from the network level.

Kindly advice so that if one NTP server went down the NTP switching done automatically.