Start by checking if you can connect via telnet from the VM running the second node to the VM running the first, using the same IP address and port (i.e. 10.0.2.15 and 4255 in your examples). That should indicate whether it's a firewall or networking problem between the VMs, or something in the MultiChain handshaking stage. You can also examine the debug.log file in the appropriate blockchain directory on both VMs to see if there are any clues there. And finally, please ensure you are upgraded to the latest version, 1.0 alpha 27.