It is not that straightforward when you connect a 4G dongle. Not ony there is probably a new IP address everytime, but also you can not just make a request over the Internet to an IP address behind some NAT. Telecomm companies do not provide static IP address to cellular connections. This is how our Internet manages to survive even though number of Internet users have grown way more than the number of possible IPV4 addresses.
There are two known work arounds, VPN and Dynamic DNS service. You can take a look at them. In both cases you are assuming that thruough 4G your odroid is connected to Internet and your client laptop is also on Internet.
However if you can hold, we have Cloud APIs coming out in next few days. With these API's you will be able to control, monitor your drone from cloud. All you have to do is to connect your drone to Internet through 4G, wifi or whatever you have. Then use the FlytConsole Cloud app to control your drone. Also all the APIs will be accessible through cloud.
You can participate in beta trials if interested. We have already done lot of internal testing and announcement will be made soon. Thanks.