After ArcGIS Enterprise is installed with the firewall turned off, can I re-enable the firewall on the physical machine where the VM where ArcGIS Enterprise is installed is located? ArcGIS Enterprise is installed on a VM.
You will need to make sure that you have all the ports open for the product installed. Here is the information for Portal in terms of ports needed: https://enterprise.arcgis.com/en/portal/latest/install/windows/ports-used-by-portal-for-arcgis.htm
This information is available for each product in the installation guides: https://enterprise.arcgis.com/en/documentation/install/
You can also review ports used by machine in this handy visualization: