Thanks for your response, jggimi. You are goddamn right about the setup - easy, with several commands - but troubleshooting to actually make it work is a lot more complex...
Last screenshot (ping from server to client) is confusing me a lot - packets just dissappear somewhere between tun0 and vic0! Firewalls are 100% identical on server and client...
I forgot to mention that a ping sweep (10.0.1.1 to 10.0.1.10) from the client succeeds only on 10.0.1.1, and from the server - only on 10.0.1.6, i.e. they can only ping their address as shown in ifconfig tun0 (4th screenshot)
I hope somebody sheds some light in here