this is from updatemanager 6.5 documention
TCP Port Number
The port used by Update Manager to connect to vCenter Server.
The port used by ESXi hosts to access host patch downloads over HTTP.
The port used by Update Manager to push host upgrade files.
The port used by Update Manager Client plug-in to connect to the Update Manager SOAP server.
The HTTPS port used by Update Manager Client plug-in to upload host upgrade files.
Firewall rules between vSphere Update Manager (VUM) and ESXi host (6.x)
ESXi_host => VUM TCP: 80,443,9084,9000-9100
VUM => ESXi_host TCP: 902, 735(obsolete VM OS updates)
Can I confirm?
I would believe that the port 735 / tcp for VM updates is still used for the VMtools updates (agreed that the VM OS updated are obsolete), but for tool updatesis 735 still the port used?