I just want to share my experience
We had this problem as well as other ones! so how we solved our problem. We had time and FQDN issue, so we changed our NTP server and used FQDN instead of IP address in the configuration of our Application Remote Collector (when you want to add Application Remote Collector in vROM). Remember this, I found it helpful, "the credential used to add vCenter into vROM must have the privilege to install the agent on VMs." So we used a domain credential.
I hope this information can be helpful