A used Lenovo M800 SFF (skylake) PC (i3 suffices) starts around 50 EUR/ USD, ~16-18 watts idle. Add in two low-profile 2.5GBASE-T cards for 20-25 EUR/ USD each (RTL8125/ RTL8125B); ~100 bucks each, if you want to go 10GBASE-T (Aquantia based). RAM- and main storage sizes don't matter (much).
Gives you the performance, no excuses, no questions asked, for a reasonable price - and at an okay'ish power consumption (other x86_64 hardware might get you down another 5-6 watts).
Other vendors exist and may even provide better results, this is just the one I have idle power consumption measurements for at hand.