How to combine 3 servers with internal gray addresses and white external ones?

Question

VPN

Task:
there are 3 VPS geographically spaced around the world
2 machines in the Russian Federation and one somewhere in Europe,
they need to be combined with each other that they were in the same address space ip addresses out of 10. * (gray ip)
I look towards any tunnels or vpn , but they all come with traffic encryption, but I don’t need it, are there any other options?
since encryption eats up a certain CPU resource and slows down the speed between machines, well, or make it as minimal as possible.
And yet - it is critically important that the services (daemons) be able to keep the connection inextricably constant, if some machine goes into reboot, it should automatically connect to the main machine (well, that is, stupidly self-start the tunnel)

Answer 1

10.* gray addresses - without NAT translation or tunneling, there is no way to merge through the global network.
There are different options for tunnels, not necessarily with encryption
. Inextricable connectivity is achieved by creating several, including oncoming tunnels.

Answer 2

It is quite possible to configure vpn without encryption, but in general - it seems to me that you are overestimating the influence of the same AES, which all processors have been able to do at the instruction level for a long time, on its load and network bandwidth.
Regarding auto-connection - the same openvpn and warguard reconnect automatically by default.

Answer 3

Try ZeroTier VPN, it combines clients into one L2 network. Its peculiarity is that all clients can be behind NAT, while traffic will be transmitted directly if possible and you will not have to raise two interfaces on each client. The free plan should be enough.

Answer 4

https://www.junmajinlong.com/files/openvpn-cookboo...

Answer 5

pptp. Unsafe, least resource-intensive
OpenVPN - safe, almost everywhere and always crawls
...

Answer 6

In one network - well it is not possible in any way. And in general, according to this picture, each server holds two tunnels. In principle, the task is quite solvable, but they will not and cannot be in the same network.