The digitalocean (or any VPN provider you trust) is still no doubt a good solution.
This being said,
- What they provide is probably based around the client.conf and server.conf
files you can see over there: All the VPN IP config is in the server; if needed change its config and define a new VPN network, restart the server and after a little while the clients should be back on the new VPN network.
- If you're intrigued by bridging, you could see this
. It describes bridging with OpenVPN acting as a sort of DHCP server for its clients (server-bridge mode). Don't miss the How-to
- If you're intrigued by bridging in peer-to-peer mode (external DHCP server etc, OpenVPN doing only the bridging) combined with anonymous bridging, you could have a look at this post
. It is a different application, but the Pi in this case has the same dilemma: it lives on LAN 192.168.1.0/24 and needs to let machines behind it access a VPN network numbered 192.168.1.0/24 as well.