I wouldn't bother with the Virgin app for checking the Wi-Fi.
use a good Wi-Fi analyzer/scanning app - several free ones for Android, inSSIDer or Netspot for Windows/Mac or even Airport Utility for iPhones.
check Wi-Fi environment and run speed tests with thir party sites (Ookla, Samknows) at the locations
Check for any interference from neighbouring hubs/APs.on same channels - try changing channels.
If you still have such issues get a good third party router or add an additional access point.
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I know a bit about Wi-Fi, Telecoms, and TV as I used to do it for a living but I'm not perfect so don't beat me up... If you make things you make mistakes!