Couple of questions:
What’s the status of the Hyper-V swtich? Should be “internal” and named "DockerNAT"
When you install the VM on Hyper-V the posh script of the beta will create an hyper-v switch as NAT network on the ip range “10.0.75.0/24” with gateway “10.0.75.1”. Can you ping the gateway?
If you change the Switch of the VM will not work due the fact that the docker installation is setup to look for the “10.0.75.x” network.