With my limited knowledge of setting up but with experience of using it:
We have a P620 running Rocky and happily serving the iMacPro in the secondary room over 10 Gig. We have an internal IcyDock with 8xSSDs as a Stone.
Most important thing to consider would be if you’re able to run Stone&Wire server on an old Z840, since Flame is not supported on that hardware anymore, as far as I remember.
Theoretically speaking 10Gig should give you 1 GB/sec transfer which would be enough for 4K 10 bit at least, but practically would depend a lot on your network setup.
Again, more knowledgable people will probably chime in…
Awesome, thanks for confirming that would work…
I watched a video of someone doing the whole thing on a server running Proxmox. That got me thinking the hardware wasn’t as important for the system that just serves up stone and wire.