How to connect 2 offices via VPN?

Question

openvpn

There is very little knowledge, tell me some detailed guides, I installed an openvpn access server, but I can’t understand how to work with it, where and how to generate certificates to connect a router,
routers at both ends of the zyxel USG
The problem is that the BC provider has its own routes routers do not see each other, you need to make sure that vpn is on the side (for example, VPS) and offices clung to it

Answer 1

you don't need access server, just openvpn server

Answer 2

The simplest solution when you need it quickly and there is no time to figure it out.
p.umputun.com/p/2014/08/12/svoi-sobstviennyi-vpn-z...
But then I would advise you to sit down and figure it out.