Time is very important for the controller cluster so you must have valid NTP servers. Additionally all of the other nodes use the controllers as their source NTP so in the environment the controller's NTP setup is very important. The fuel-master ntp isn't as important but you can change that if you need to. The 'no server suitable for synchronization found' is the problem as the ntp_check verifies that we can actually get a valid NTP response from the provided servers.
Time is very important for the controller cluster so you must have valid NTP servers. Additionally all of the other nodes use the controllers as their source NTP so in the environment the controller's NTP setup is very important. The fuel-master ntp isn't as important but you can change that if you need to. The 'no server suitable for synchronization found' is the problem as the ntp_check verifies that we can actually get a valid NTP response from the provided servers.