I would like to find out the cheapest solution to do this. I know there are free VPNs but the Problem is that I will not be able to connect to the miners interface (at least I did not found out how). The best option for me would be one that does not require a normal pc, but something small ( I need to do this for more miners which are located in a different location)
Thank you
Well there is your problem. The whole point of a VPN is to have a bunch of remote things look as if they are in a LAN you also belong to. So you install a VPN server somewhere (there are plenty of Free and Open Source solutions) and then make all your remote locations use it.
If you don't understand this, maybe you'll have to hire someone to do it for you...
VPNs are not meant for anonymity or obfuscation, if you manage to achieve a bit of that, its more by accident than intention.
Any raspi or similar embedded computer can do these things and much more.