As a user, when you create a new host backed by a vmware VM you have to select both the subnet and the VM network to correctly provision a VM.
This is very error prone as a lot of users forget to set the second select field correctly. This causes the hosts to not build correctly and has to be corrected manually. In addition, Foreman does not allow updating the VM right now (#18304).

The VMWare network matching the subnet should be selected automatically when the subnet is changed.