You need to have everything dialed in to peg the meters on a 10G link with consumer-grade hardware. Disk, memory, packet sizes, drivers…everything. It’s why it’s taken so long for 10G to reach the consumer market; most PCs couldn’t make decent use of it until recently, and then only at the high end.
My fastest results here are in the 6-7 Gbit/sec range to an RB4011 router running my iperf3 container, a CPU-based test, but I’ve red-lined a CRS328 in a pure switch chip test.
(9.4 Gbit/sec is 10 Gbit/sec minus packet overhead and such. It doesn’t get a lot faster without tweaks like jumbo packets, which I didn’t need to achieve the linked result.)
Ip6 is still rocket science for me
This guide of mine may be of some use to you, then.
I didn’t link it earlier because it appeared you’d gotten the basics down, and it was written for a different ISP, but perhaps you can still squeeze some juice from it.