@JayKay50 

To put a Virgin Media Hub 3 into modem mode, access its settings at 192.168.0.1, select "Modem Mode" in the menu, and apply changes. The Hub 3 will reboot, and its base light will turn magenta (or red) to indicate it is in bridge mode, disabling Wi-Fi and activating only port 1 for your own router. 
Steps to Enable Modem Mode (Hub 3)

•     Access Settings: Open a web browser and enter 192.168.0.1. Log in using the password found on the bottom of the Hub.
•     Enable Mode: Select "Modem Mode" from the left-hand menu, check "Enable Modem Mode", and click "Apply Changes".
•     Cable Connection: Once the hub restarts, connect your third-party router to Port 1 of the Hub 3.
•     Confirm Status: The bottom light will change to magenta or red. 

Crucial Notes & Troubleshooting

•     Port Restriction: In modem mode, only the first Ethernet port on the Hub 3 works.
•     Accessing Settings Post-Modem Mode: You can access the Hub 3 settings while in modem mode using 192.168.100.1.
•     Third-Party Routers: Ensure your own router is set to use DHCP for its WAN connection to get a public IP.

Here's how to add your TP-Link PLC to an EasyMesh network.

Here's the PLC models that support Easymesh.