It’s a common scenario: you’re ready to jump into a remote session, but TeamViewer refuses to connect. Often, the culprit is your firewall. Because TeamViewer facilitates remote access—a high-security activity—your system’s built-in defenses or third-party security software might flag it as a potential threat.
Click the button at the top (you may need Admin rights). Scroll down to find TeamViewer . Ensure both the Private and Public checkboxes are ticked. teamviewer blocked by firewall
Firewall blocking TeamViewer – unable to connect to remote devices It’s a common scenario: you’re ready to jump
TeamViewer.exe to the "White List" or "Trusted Apps" list. 4. Restart TeamViewer on Both Ends Sometimes the "blocked" error is actually a temporary glitch in the session. Simply closing the app on both the local and remote computers and restarting it can refresh the connection and clear minor network blocks. 5. Check Your Corporate or Router Firewall If you’re in an office, the hardware firewall (like a Cisco or SonicWall device) might be blocking remote access tools. Corporate: Contact your IT department to see if they have restricted TeamViewer for security reasons. Home: Log into your router’s settings and ensure that "UPnP" (Universal Plug and Play) is enabled, or manually forward port 5938 to your computer’s IP address. Pro Tip: If you frequently run into "connection blocked after timeout" errors, ensure you are using the latest version of TeamViewer, as older versions may be flagged as suspicious by modern firewalls. Would you like a step-by-step guide for a Click the button at the top (you may need Admin rights)
If you’re seeing "Not ready. Please check your connection" or similar errors, follow this guide to unblock TeamViewer and restore your connection. 1. The Quick Fix: Windows Defender Firewall
TeamViewer blocked by firewall – outbound connections failing