VM on Hyper-V can't access mapped drive on its host immediately after rebooting host

Host machine is running Windows 10 running Hyper-V as the hypervisor. Host machine has created a network folder share with full permission to Everyone.

An external virtual switch has been configured and is being used by the guest.

Guest VM is also running Windows 10.

Guest VM has successfully mapped a drive to the host's network share. Software running on the VM access the mapped network drive to write files.

After I reboot the Host, the Guest VM will resume, however when the software running on the VM attempts to access a folder on the mapped drive it gets an error that it doesn't exist. The software then tries to create the folder and also gets an error.

I logged into the guest VM and I can see in File Explorer that the mapped drive has a red cross through it's icon (disconnected state?). Clicking on the drive gives an error and it doesn't connect. It doesn't seem to self-correct after.

I got lucking one time when I manually type the hostname as a UNC path into the address box and press enter, it browses successfully and then I browse to the same folder and it works and the mapped drive connects.

Can anyone help explain what is going on (is the VM starting faster than the Host can share the drive or before the host advertises itself on the 'network'?) and offer suggestions to fix or workaround (delay service start-up)?

UPDATE: this latest time it didn't work - just kept getting network error 0x80070035 - the network path was not found. This time I had a look through Event Log and found an entry from "DNS Client Events", Event ID 1014, Text "Name resolution for the name .local timed out after none of the configured DNS servers responded." I checked my DNS settings and for my local adapter it had been changed to 127.0.0.1. I suspect my VPN client (Viscosity) has done this automatically. I've asked them for assistance.