I'm trying unsuccessfully to remote desktop from a linux mint 18.3 to another linux mint computer over the internet, without messing with the routers settings or manually opening ports, something similar to TeamViewer for Windows. I've read many links but all involve some manual changes in the remote routers, which I'm not able to do.
I've installed remmina, a vnc server, enabled Desktop Sharing to both computers, but I find it impossible to connect. Also I'm trying it with any protocol, VNC, SSH, NX. So my question is, is there any free software that will take care of the port settings seamlessly, to simply enter the remote local IP and establish a connection? Note, this connection is over the internet.