Installing/Running Ubuntu 14.04 as VM on XEN (network issues)

I have been having issues installing Ubuntu 14.04 as a vitual machine under XEN, and after I was successful installing it, doing updates it would also have issues (network related) it tends to lose connection or not be able to resolve, not sure which, but it is very annoying. I installed TeamViewer and could not get it to connect a single time. Any tricks or hacks to get a reliable network connection on Ubuntu under XEN? (i.e. clone a certain MAC address and nic model under the .cfg/.xml file on XEN?)

Thanks!