@Buddya1 

Thanks for reaching out. I understand that after your Xfinity xFi Gateway modem rebooted, your Deco Mesh (M9 Plus) did not automatically reconnect to the Internet, even though the modem was back online. You'd like to know how to restore the Internet connection without having to manually reboot the Deco.

Here are some steps you can try to resolve this issue and help your Deco Mesh system reconnect to the Internet:

1. Check your ISP connection: Connect a computer directly to your modem using an Ethernet cable to confirm that the Internet is working from your ISP.

2. Reboot your modem and Deco: Sometimes, rebooting both devices helps them re-establish a connection. Unplug both the modem and Deco, wait 10 seconds, then power them back on (modem first, then Deco).

3. Replace Ethernet cable and port: Try using a different Ethernet cable between your modem and the main Deco unit, or connect to a different Ethernet port on the Deco.

4. Change DNS settings: Make sure your phone is connected to the Deco Wi-Fi network. Open the Deco app, go to MORE > Internet Connection > tap 'IPv4 Connection' > DNS Address. Select 'Manual' and enter '8.8.8.8' and '1.1.1.1' as the primary and secondary DNS servers.

5. Mac Clone: If your computer has Internet access when connected directly to the modem, but Deco does not, try configuring Mac Clone on Deco. Follow the instructions in this FAQ: https://www.tp-link.com/en/support/faq/2925/

Additional settings to check:
• In the Deco app, go to MORE > Advanced > IPTV/VLAN. If the IPTV port is enabled, do not use it to connect to your modem.
• Go to MORE > Advanced > WAN Port. If this feature is enabled, ensure you are using the correct Ethernet port on the Deco to connect to your modem.

If the issue persists after trying these steps, please contact TP-Link Support and provide details about the troubleshooting steps you have already taken.

Let me know if you need further assistance!