Succesfull backups need port 443 open to ESXi

For successful backups, port 443 needs to be open to ESXi.   VDP backup solution is a prime example how this issue can escalate with both hotadd and NBD failing.

With port 443 disabled to ESXi we see errors similar to below.

2018-02-13T21:58:01.062-02:00 avvcbimage Info <16041>: VDDK:2018-02-13T21:58:01.062+01:00 error -[7F3C07709700] [Originator@6876 sub=transport] Mounting VM vm-3879 using transport hotadd failed : Cannot access datastore for one of the disks of Virtual Machine VMname..

2018-02-13T21:58:01.062-02:00 avvcbimage Info <16041>: VDDK:2018-02-13T21:58:01.062+01:00 error -[7F3C07709700] [Originator@6876 sub=transport] Cannot use mode hotadd to access [VMFS-DATASTORE-LAB] VMname/VMname.vmdk: Cannot mount using this method. (Mounting VM vm-3879 using transport hotadd failed : Cannot access datastore for one of the disks of Virtual Machine VMname..)

Info <12006>: hotadd transport is recommended for faster backups and restores and less exposure to network routing, firewall and SSL certificate issues.
ne or more of these items may be preventing use of hotadd transport with this VM:

To test port 443 to ESXi is open we can use the following commands.

From VDP to ESXi 

curl -kv esxhostname.fqdn:443

From ESXi to  ESXi 

nc -z esxhostname.fqdn 443