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Error: Socket bind failed on local address

OpenVPN connections can be configured to bind to a local address and/or port number when connecting. Binding can be thought of as attaching to a fixed address and port number on the local computer. While fixed binding is needed for the OpenVPN server and for site-to-site connections, it's typically undesired for normal client VPN connections.

If you're seeing a "TCP/UDP: Socket bind failed on local address" error message in the OpenVPN log, it means your VPN connection is configured to bind to a fixed local address and/or port number, and that this address/port number is unavailable. This can normally be resolved by turning off binding like so:

  1. Open Viscosity's Preferences window and make sure the Connections toolbar icon is selected.
  2. Select your connection and click the Edit button.
  3. Click the Options tab.
  4. Tick the "No Bind" checkbox and click the Save button.

If you're trying to connect two VPN connections simultaneously, and you receive a "TCP/UDP: Socket bind failed on local address: Address already in use" error message for the second connection, it means that both VPN connections are configured to bind to the same local port number (which isn't possible). Enabling the "No Bind" option for both connections will typically allow both connections to connect.