FRITZ!Box 4020 Service - Knowledge Base
Shared files and printers on a computer are not available over the Internet
You cannot access shared files and printers on remote computers over your FRITZ!Box's Internet connection. Other connections using the SMB or CIFS protocol also cannot be established over the FRITZ!Box's Internet connection, for example connections to Strato HiDrive. Connections from the Internet to the home network that use the SMB or CIFS protocol are also not possible.
- For security reasons, in the factory settings the FRITZ!Box blocks all access over the Internet to the TCP and UDP ports 139 and 445 ("NetBIOS Filter") that are used for file and printer sharing.
1 Configuring the application to access the Internet without NetBIOS
- Configure the respective application so that it uses secure transfer protocols such as VPN, HTTPS, or SFTP instead of the SMB or CIFS protocol. Refer to the manufacturer for information on the necessary settings, for example consult the manual.
If you cannot or do not want to change the configuration of the application, disable the NetBIOS filter in the FRITZ!Box:
Important:When the NetBIOS filter is disabled, computers in the home network may be subject to more frequent attacks from the Internet. Therefore, set up a firewall on all computers in the home network.
Now you can use applications that must exchange NetBIOS packages with the Internet. This means that you can also access the shared files and printers on remote computers.