We had virgin installed yesterday and after running a speed test we saw we're only getting around twenty to thirty Meg as opposed to the 300+ we're paying for. We called the help desk and they log into the router and then asked us to run a broadband speed test with them online. At that point the broadband speed jumps to about 180meg (still just over half of what we pay for) and the technical support people say there's no fault on their end or with our router. Unfortunately a couple of minutes after ending the call the speed drops back down to twenty.
Thanks for your help everyone, it was because I was using chrome browser to run speed test on my laptop. Once I'd switched to Edge it gave a speed of over 400 Meg which was nice as only paying for 350.