After you have bought your WIFIPLUG from here
This guide will show you how to setup 2.4 GHz on your Virgin Media Super Hub or router manufacturer.
Not your router? Click here for more setup guides.
Open a web browser and type "192.168.0.1" into the URL bar then press [Return]/[Enter] to load the webpage.
When the page loads, login using the router's admin credentials.
After logging into your router, click the "Wireless Network Settings" button.
Locate the "Wireless Band" settings option and check the "2.4 GHz" option. For maximum compatibility, ensure that the 5 GHz box is unchecked. After setting these options, click "Save Settings".
Select a single channel for best results 1-11 ONLY
After making these changes we recommend restarting your router so that the new settings can take effect.
Step 6 [optional]
Once your router has restarted and you're able to access the Internet again you can proceed to setup your WIFIPLUG device. For help setting your WIFIPLUG device up, click here to return to the Support Home Page, choose your device and select the relevant setup guide for your mobile platform.
Note, feedback from other smart plug manufacturers - https://community.virginmedia.com/t5/Networking-and-WiFi/Smart-plugs/td-p/3895567