Help please re Connection Issues after updating to Full Fibre with Open Reach UK

[Thorrrr]

OK
I have had no crashing of loss of signal yet. But i have done some testing today directly with a wired connection directly on the modem.
I have tried with a laptop with a USB 3.1 connection direct connect with my 900mb the best i can get is about 456mb i have tried about 6 different servers locations but never pass 500b mb.

Id i attach the Plusnet modem i get 896 mb instantly and 160mb upload  which is what i was expecting . So everything points to my Opnsense router but not sure how to check where the bottleneck is!

I have ordered Dell INTEL I350-T4 Low Profile PCI-E 4-port Network Card PN: K9CR1 to attache to the PCI on my Zimaboard. Not 100% sure but from reading this should be better as a NIC compatibility.

ANy thought on how i can check what is throttling or bottle necking the sped ?

What other services (if any at all) do you have running on your OPNSense installation?
I noticed that your Zimaboard uses a fairly weak Celeron processor. It's possible perhaps that that is where your bottleneck is coming from

I have Adguard & Crowdsec plugin also running  see here https://xbackbone.osopolar.cloud/ZubU1/TuGICeZA64.png