Windows 10 to Windows 10 authentication when off-domain

I have a laptop running Windows 10 Pro, domain joined to a Server 2012R2 AD.

I have Hyper-V running on the laptop with a Windows 10 Pro guest, also joined to the domain.

I have a shared folder on the host which I connect to from the guest so the two can share the same files using different software.

The Problem: When I am not connected to the domain (locally or via VPN) and after a reboot of the OS I cannot authenticate from the guest OS to the host OS shared folder. I can ping by name and IP as I have an "Internal only" switch set up in Hyper-V and the guest OS has a hosts file entry for the host's IP on this switch. I also have "external" networks set up on the guest for network and internet access. So communication is fine, I think it just needs to authenticate with the AD DC.

I use the same domain user name on both host and guest. When the DC is available the guest connects the mapped drive and I can browse via UNC without entering a username and password. When off-domain it prompts for the username and password but nothing I put in works, it just says "The system cannot contact the domain controller to service the authentication request". When off-domain I can log into Windows using the cached credentials.

Is it possible to allow this kind of authentication? Is there an alternative if any changes would be considered insecure or bad practice? One alternative I thought about was to connect my OneDrive to both guest as well as host, but this means I have to be online for files to sync between them so not ideal.

Any help appreciated.

Cheers

Not a direct answer but it's a working solution: create a local user account on the host (not domain) and use that when connecting in from the guest OS.

This avoids the need for AD authentication while retaining some level of security.

I ensured I granted the minimal level of NTFS permissions on the shared folder and set a very strong password.

Hope that gives an idea to someone else with similar issues.