[44net] need help configure gateway on ubuntu

I am trying to configure the tunnel on Ubuntu 18 on a cloud VM just to figure out how the configuration works. I am looking at http://wiki.ampr.org/wiki/Ubuntu_Linux_Gateway_Example and have trouble configure the interface. I have configure auto ens4 iface ens3 inet static address {my allocated IP} netmask 255.255.255.252 However, the ifup ens4 command will failed to bring up ens4 interface. And of course when running ampr-run.sh and find_pass.sh will resulted in Setting SO_BINDTODEVICE: No such device. Any advices on how to set it up on Ubuntu 18? Thanks Kun