Thank you for your detailed response.
I have often used third party speed tests and they give similar results to the Connect App. The difference is that the Connect App also shows the WiFi speed, which doesn't seem to be the case with third party sites (at least the ones I use).
I have now got a Virgin Pod. It comes free with my package, so there was no point looking for an alternative. My last score was 190 Mbps compared with the 1 I had before. So far everything seems much better, fingers crossed. I did try a WiFi extender in the past before I heard about Virgin Pods and that didn't help at all.
I can no longer use a wired connection as it doesn't seem to work any more. I think probably the wire has got broken somewhere. I had it installed many years ago, and as it has to go from where the modem is installed in a room downstairs up to my bedroom where I have my office it would be an expensive job to replace it.
My contracted speed is the top one - 500. Although my current 190 is well below that, the hub speed of 626 is above it, and I assume that means I am getting what I am paying for. I can't blame Virgin for a loss of signal because I need to work on the computer and watch TV in a different room from where the hub is installed.