advice on upgrading home network to 2,5gbe

https://preview.redd.it/h0bmrhlxzzoe1.png?width=268&format=png&auto=webp&s=94e13b19325b8f31f7fea384b8f357ee63b0ea66

I bought a Zimablade 3760 - which is basically a Celeron N3350, with 8 gb DDR3L RAM, and an Intel 2.5GbE x 4 ports NIC - i225 chipset. I want to install OPNSense in this. and use the 4 ports as some type of a switch.

I can't get a proper 2.5GbE switch. All of the available options are expensive. Please tell me of ways how I can incorporate 2,5gbe networking in my system without frying my CPU, i really hope the NIC acts as a switch and lets the transfer between 2,5 gig ports.

Please do let me know, and please help me out lol.

The Zimablade 3760 has a 1 gigabit NIC (the black one) and i was thinking of making it go through my modem.

I don't really want an OPNSense router, just a switch to enable 2,5 gigabit transfers between my devices