At first I ran the OpenVPN server in my asus router. This was easy to set up. Because of the heavy encryption of the datastream the router cpu was overloaded. Because of that I installed OpenVPN server on a windows machine. It did not work. Had some kind of routing issues. Ended up with lowering the encryption and kept OpenVPN server in my router. Client setup was not hardCome on that's not really hard.L2TP uses udp.I'm using an L2TP VPN which is built into Windows, I'm not sure whether that uses TCP or UDP. I spent a few hours trying to set up OpenVPN a while back and couldn't get it to work (and I'm a very experienced user). The official guides were out of date and not detailed enough, and even once I finally got all the certificates sorted and all necessary ports open and checked, it wouldn't even connect, let alone authenticate.
I recall that setting up OpenVPN was hard
Just built a new box for one of our customers last week.
Did you try on linux or windows?