@Spb67 Here are the DHCP settings in VR2100:

Contact your local support for that issue. If your device is still under warranty they probably would replace it with a new one..

@Spb67 Check out this video guide. In this post - https://community.virginmedia.com/t5/Networking-and-WiFi/Connecting-Superhub-3-0-to-TP-Link-or-other-router/td-p/3934223 you can see the steps needed.

@davegray You can read this gude for more details.

By "connection becomes horrendous and keeps dropping out" what exactly do you mean ? Describe the symptoms in details and observe the LED status of the device during these drop-outs.

Are you using the guest network for visitors ?