@Fred Eric S Thanks for reaching out. That is indeed a very common scenario in current situation.
Since the devices are hybrid Azure AD Joined, the machine would need to be direct line of sight or to be able to communicate to a DC to authenticate the user when the user tries to login. This would fail if there is no network connectivity to the corp network to locate a Domain controller.
You need something which can enable the end user to setup a VPN to your corp network even before they login.
You can consider following 2 scenarios/solution for your this solution :
1) Hybrid Azure AD join User Driven AutoPilot with support of VPN.
2) White Glove Hybrid Azure AD Autopilot (Which has 2 parts a. Technician b. user )
You will need to use intune to deploy a Device based VPN policy https://learn.microsoft.com/en-us/mem/autopilot/windows-autopilot-hybrid
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