Dear Fitpc community,
I stumbled upon the fitlet2 and I think it is the perfect solution for a homemade router running as openvpn client and server.

What is not clear to me is if I can plug in a Wi-Fi card without buying the wifi+3G/4G facet. The documentation is a bit confusing on that point.
Also, would a 4 Tb harddrive work under linux?

Thanks

fitlet2 supports a WiFi module without the need of any extension board.
Also, should you wanted to use a 2.5" drive, you'd require the deep bottom cover for a 4TB hard drive.

You can configure and observe the possible configuration options using the fitlet2's build to order website:
https://fit-iot.com/web/product/fitlet2-build-to-order/