Hi sof006
The BT home hubs I have seen generally have had stable connections, from memory they mostly have Lantiq or Broadcom chipsets and where I live we have quite poor phone lines and they do pretty decent job - are you sure its the router? Perhaps you could share some line data, there are people on here who might be able to help ...
I think the VR400 has a Broadcom chipset, you might end up with similar performance if the chipset is the same? Personally I am not a fan of TP-Link equipment due to their poor firmware support, I would go for a more reputable second hand device or alternatively flash a third party firmware.
C