“I have tried leJOS and it is hosted in the ev3 brick which can be controlled by any device that is connected in the same network (is thr any solution for different network?).”
You can open the port to access the website (probably 8080 redirect to 80). Then everything can access to the server from the internet. But you have to get the online IP somehow.
“Is there any way like hosting an ASP.net online website somewhere outside rather then on the EV3, so i can still able to control ev3 during my oversea trip.”
You can run a webserver on a computer which can access the EV3 through the MonoBrick communication library.