Final post.

Based on POEs feedback and pinging the router I discovered it was a problem with the router. As noted this was a replacement router sent by the ISP - and the previous router had worked fine in my old apartment with the same network setup. Only two of us here and the other person isn't much of an internet user so my only conclusion is that either electrical interference was causing the problem, or my smart heating hub (which I got when I moved here) was causing the problem.

Today I set up an ASUS third party router and set my Virgin Hub 3 to Modem mode, and I'm currently three glorious hours without packet loss.

Thanks all, could not have done it without pingplotter.