Your company has a main office in London that contains 100 client computers.
Three years ago, you migrated to Azure Active Directory (Azure AD).
The company's security policy states that all personal devices and corporate-owned devices must be registered or joined to Azure AD.
A remote user named User1 is unable to join a personal device to Azure AD from a home network.
You verify that other users can join their devices to Azure AD.
You need to ensure that User1 can join the device to Azure AD.
What should you do?