Which operating system should I choose for my router?

Question

Operating Systems

I want to assemble my own router, I have such a config - xeon e3 1220v2, Intel S1200BTL motherboard and 8GB of RAM. Since there is a large file server on the network, I want to install one Mellanox MHRH2A-XSR and two HP NC523SFP.
As I see it.
Some network QSFP card is installed in the file server, the wire goes from the server to the router, and from the router via SFP + traffic is distributed to clients. And yes, three clients will be connected directly to the router, and the rest of the clients will be connected through a switch (that is, the switch will be connected to the router via SFP + too).
So, what operating system to take for this case, I considered pfsense, but everyone says that it does not work stably at such speeds, its maximum is 5-7Gbps, I didn’t find anything sensible about opnsense, how it behaves at such speeds . What can you advise?

Answer 1

Here, most likely, an L3 switch is needed, and not a soft router. It would be desirable to learn, proceeding from what needs the router is necessary.

Answer 2

I'm sorry, but WHY does the computer have to be a router \ router? Ready-made solutions in bulk, Mikrotik for example, with SFP ports is available. Everything has already been invented for you, it remains only to customize it to your needs.

Answer 3

You need to put the one in which you understand and you can solve the problem if it arises.

Answer 4

It is necessary to test (с)
I do not think that pfsense, specially designed for processing network packets, will be much worse than tuned regular Linux.

Answer 5

Install Linux if the hardware pulls it up.
If not, then roll FreeBSD.

Answer 6

Why build a router? Are there any requirements that cannot be implemented, for example, in Mikrotik?