Resolving QuickBooks Multi-User Mode Failures Due to Firewall Windows Firewall can prevent multiple users from accessing a company file simultaneously. Configuring exceptions and verifying port access restores Multi-User Mode, allowing team members to collaborate without interruptions while safeguarding your financial data from unauthorized access. ----- https://www.apsense.com/article/868548-methods-to-fix-windows-firewall-is-blocking-quickbooks-issue.html