@Richiev4 

The reason why the WiFi goes down is that the modem disconnected from the network I guess. As per your description, I guess the Virgin Media connection may not be stable. You can monitor the internet LED on the AX50 router when the WiFi goes down, will that turn orange/red? If that is the case, you may get back to Virgin Media to ask for suggestions.

If they confirm the modem and the internet are stable, then try to follow Kevin's suggestions in this thread to check if you can resolve it.