Creating a VPN for communicating two different boards
Solution 1:
I have decided to use OpenVPN as the solution to my problem. Even though VXLAN is the most compatible and easiest solution, it lacks security measures and thus I decided to use OpenVPN.
OpenVPN allows ethernet bridging (layer 2) and this is enough for my purpose. It is slightly harder to configure and install compared to VXLAN.
Thank you to everyone who have commented and helped.