pfSense is what I use, after going thru the process you are going thru, trying out different things and trying to find one that works well. Curious why you need three network connections though. I would suggest good WiFi access point as entirely separate devices.
haha I remember several years ago (Windows XP times) where I took an old 486 and with it made my own router and worked as a charm
Myrrh, one needs 3 to set up the NICs properly, so one is connected to the modem and the other to the 8 port switch that sits behind it, to distribute the whole thing around the house... So, it's as modem from the net provider to the pfSense mini PC router, to 8 LAN port switch, then to the rest of the house... I prefer cabled up connections, if I can help it. And if not, then the pfSense mini PC router does have 2 WiFi antenae and I have a WiFi extender (plugged into an 8 LAN port switch), at the opposite part of the house. But it;s a palaver to set it up properly, as described in the link re. "bridging"... Mind, a new version of pfSense is now out - must check it out...
I still don't get three, you mentioned purpose of two of them. Is one of the built-ins a wifi adapter? That would explain a 3rd network connection which would be the 2nd wired connection.
You must inform yourself, Myrrh. Read the link to do with bridging - then you will understand. Today I did it again and it would not work properly (WiFi in particular) until bridging was done... Even after I added WiFi to the mix (you must do this after the installation of pfSense). I sent the feedback to the company that made the mini PC I bought from them and how it actually works with pfSense... I really tried, tested with various tutorials. Only the one with bridging really worked properly, in every sense. But I have not heard from them again... Btw, after I added 5th NIC - it couldn't be shown, it was not seen by the system... It's a bit weird but if you are patient and do it as advised - it would work...