Just to state the obvious, the full profile is to the router, you need a device with a 2.5Gb NIC (or a 10Gb NIC that supports NBASE-T) to get faster than gigabit over a wired connection. If you don’t, then you get gigabit speeds as described.
Do a test to YouFibre London using speedtest and post the results. I’ve noticed that since migration my normal speedtest default place it throws up is Nottingham, this is about 20% down on speed (1gb), if I do a speedtest to YouFibre on London I get full speed (1.2gb).
Somethings slowing it down if it doesn’t go to London, YouFibre Manchester is 20% down also so I get 1gb.
Yayzi did respond asking if any QoS etc on the router. Also it should be noted that speedtest servers themselves may not have the bandwidth for the full 2.5 speed.
I was having similar issues to yourself, which I finally resolved last night.
In my case, I was using an Intel i226-V 2.5Gbe nic, I have now switched to a Realtek 2.5Gbe nic, and I can now receive the full 2.3gbps up and down without issues.
Maybe worth a try if you are also using an intel ethernet port.