@Boykin 

Try the steps listed below, if none of them resolve your issue please let me know ty.

The error "Failed to save the information IPV6 deco" when configuring IPv6 on a TP-Link Deco device usually indicates an issue with the setup process or compatibility. This can stem from incorrect connection type selection, missing information, or incompatibility between the Deco's firmware and the ISP's configuration. 

Here's a breakdown of potential causes and troubleshooting steps:

1. Incorrect IPv6 Connection Type:

• Verify with your ISP:

  The most crucial step is to confirm the correct IPv6 connection type (Dynamic IP, PPPoE, 6to4 tunnel, or Bridge) provided by your internet service provider.

• Incorrect settings:

  Ensure that you've entered all required information (username, password, etc.) accurately for the selected connection type, according to TP-Link support.

• Example:

  If your ISP uses PPPoE, and they provide separate credentials for IPv4 and IPv6, you may need to disable the "Sync IPv4 Account" option and manually enter the IPv6 credentials. 

2. Deco Firmware and Hardware Compatibility

:

• Check for firmware updates:

  Ensure your Deco units are running the latest firmware, as updates often include bug fixes and improved IPv6 support. 

• Compatibility issues:

  Some older Deco models might have limitations with certain IPv6 features or connection types. If you have a mixed network with older and newer Decos, this can cause issues. 

• Specific features:

Some features like "Connection Preference" might require all Deco units in the mesh to support them. If they don't, you may encounter errors when configuring them, according to TP-Link Community. 

3. Other Potential Issues

:

• VPN Interference:

  An active VPN connection on your phone or computer can sometimes interfere with the Deco's ability to save IPv6 settings, says a user on TP-Link Community. 

• Browser Issues:

  In some cases, browser-related issues might prevent settings from saving. Try using a different browser or clearing your browser's cache and cookies. 

• Resetting the Deco:

  A factory reset of the Deco units can sometimes resolve underlying issues. This will require reconfiguring your network from scratch, suggests a user on YouTube. 

Troubleshooting Steps:

1. Verify IPv6 Connection Type: Confirm the correct IPv6 connection type with your ISP (Dynamic IP, PPPoE, 6to4, or Bridge). 
2. Check for Firmware Updates: Ensure your Deco units are running the latest firmware. 
3. Disable VPN: Temporarily disable any VPN connections on your devices. 
4. Clear Browser Cache: Clear your browser's cache and cookies. 
5. Try a Different Browser: Try configuring the settings using a different web browser. 
6. Factory Reset (if necessary): If all else fails, consider resetting the Deco units to their factory defaults