How to Enable Bridge Mode on a Fritz!Box 6670 Cable

If you want to enable bridge mode on your Fritz!Box 6670 Cable, you’ll need to tweak the configuration manually. The process involves exporting the configuration file, making a few edits, and recalculating the hash before importing it back. Be careful and always do this on your own risk. This worked for me on the current 8.0.3 release.

Step 1: Prepare the configuration

Export the current configuration
Go to System → Backup and export your configuration. This creates a plain text file containing all settings.
Enable hidden LAN bridge settings
In your exported file, look for this line and update it (or add if missing):
```
lanbridges_gui_hidden = no;
```
Recalculate the hash
Use the FritzBox-JSTool to update the hash value in the configuration file. Without this step, the router will reject the modified file.
Import and reboot
Import the updated configuration back into the Fritz!Box and reboot the modem.

Step 2: Activate Bridge Mode

Turn on Bridge Mode
Go to Internet → Account Information → Bridge Mode. Enable a specific port (for example, LAN port 4) and note which one you selected.Then click Save.
Export the configuration again
Once saved, export the updated configuration file to make a new edit.

Modify the bridge settings
Find the section containing:

enabled = yes;
name = "ethport_4"; // Change to "ethport_1"
type = qos_cfg_custom;
iface = qos_lan;
rule = "ethport 4"; // Change to "ethport 1"
result {
    tos = -1;
    vlan_prio = -1;
    queueref = "realtime";
    bridgeref = "lanbridge";
    forwardref = "";
}

Adjust it so the port assignment matches the one you want to use (for example, change from port 4 to port 1).
Recalculate the hash again using FritzBox-JSTool.
Import and reboot
Import the final version of the config file and reboot your modem.

Final Tip

Don’t forget to set LAN port 1 to 2.5 Gbps mode if that’s the port you’re bridging.This ensures you can take full advantage of your high-speed connection.