An employee is unable to view in-office network folders while working at home. Which of the following is the MOST likely cause of the problem?

Untrusted software refers to applications that lack a verified publisher; its presence would not specifically block access to mapped network shares while allowing other internet activity.

Outdated antivirus definitions affect threat detection capability but do not restrict access to network file shares or enforce connectivity rules.

MDM policies can enforce security settings on devices, but MDM itself would not silently prevent a user from accessing internal folders - it would more likely display a policy violation message or restrict specific applications.

Internal network folders are hosted on servers that are not exposed to the public internet. A VPN creates an encrypted tunnel between the remote user's machine and the corporate network, assigning the device a network address that grants access to internal resources. Without an active VPN connection, the employee's home machine has no route to those private file servers.