Do you have firewall between vcenter and DR ESXi can you check if the required firewall port is opened between ESXi and VC/DNS servers, to avoid frequent disconnect of esxi to vc.
port to be opened between vc and esxi
902, 5989, 80,443,623, 8000, 8001, 6500, 514,8080
port to be opened between esxi and dns server
53, 88, 389
refer below for more information: