Another thing to note - the raw network speed is only part of the data you need.
Network Jitter is also important and I don't believe Speedtest tells you that? Latency is also important of course. And if you have ANY packet loss, you have an issue.
https://freeola.com/line-test/
Many advantages of being on a BT Full Fibre connection is both low latency and low jitter. 
All measured from my desktop which has a 1Gb connection to my 1Gb switch with 100Mb to the router which runs direct to the fibre outlet. All with 1Gb capable wiring. I pay for a 100Mb fibre and consistently get 50% more than that.
You should also check your DNS responses
I've not actually tested my home server (laptop) but wouldn't expect anywhere near the same as my desktop since it is only a laptop and has older CAT 5a wiring. But then I don't need my server to have masses of bandwidth. I do also have a NAS with a dual 100Mb network.
I should also have said that I use Telegraf to record network and other performance metrics and so can get charting and historic views on Grafana.
