If I'm reading your issue properly, you have managed to successfully join vCenter to AD, but unable to join the ESXi hosts to AD ?
Have you tried to putty connect to your ESXi hosts (may need to manually start the SSH service), and perform nslookup to your domain controller? nslookup to the domain FQDN?
If your ESXi hosts are on a separate VLAN / IP range to your domain controllers have you confirmed the relevant port access is open? Check out https://ports.esp.vmware.com/home/vSphere-7 for list of ports
