Advice on Server Build

Realtek drivers are known to collapse under the load that ZFS can throw at them.

You may be happy with it, or not.

Not bad. So you’re in the EU. What about this 59€/69€ board (with or without cooler)?

Add a Ryzen CPU and DDR4 UDIMM, preferably ECC (or, at least, you’d have the option to upgrade to ECC later).