run master on a cloud server?

edit

Have you tried setting the IPs of your master and client IP in the bashrc?

Cloud .bashrc (Master)

export ROS_MASTER_URI=http://MASTER_IP:11311/
export ROS_HOSTNAME=MASTER_IP
export ROS_IP=MASTER_IP

End Device .bashrc (Client)

export ROS_MASTER_URI=http://MASTER_IP:11311/
export ROS_HOSTNAME=CLIENT_IP
export ROS_IP=CLIENT_IP