Hi,
I am having the same outcome. In my case I narrowed it down to the change of the Send Buffer Size using Set-NetAdapterAdvancedProperty.
When the Send Buffer Size is changed, it does some sort of network reset on the VM, I don’t think Packer likes this very much and it never recovers and re-establishes the WinRM connection.
I am currently trying a number of ways to get around it, but none have worked so far.
Did you manage to fix this?
Cheers
Dave