virtualbox version 5.014 clients do not communicate with each other.

Trying to set up two windows 2012 R2 active directories and one Windows 10 Enterprise as a client. So far I am unable to get any combinations of workstations or servers to intercommunicate with each other. All clients are able to commun icate to and through the host and get Windows Updates. I have tried simplifying to the following:

I have 32 GB or ram and two 256GB SSD. Overall everything is very fast. I have the firewall turned off on all clients.

2 Windows 10 Ent under NAT or under Bridging.
I have also configured the same clients with an additional NIC so both NAT and Bridging are established. No errors, but both Windows 10 system have the same IP address under the Bridging via DHCP. If I change one to a static address again no ping between the two clients.  Same exact symptons between the two servers or one server and windows 10.

This is a quick summary of the combinations, but I have systematically worked my way through numerous Virtualbox combinations from the help files and release notes trying this and trying that each time thinking I finally got it figured out. I have gone though a number of SUN based blogs of very similar scenarios by frustrated people.

What am I doing wrong. I can't work on it right now as I am at work