I set up VNC server thanks to this tutorial but I realized that I can access to my r-pi only on the same network. So, I would like know how to access my r-pi while I am on another network and how to set a fixed IP for each r-pi I wish to monitor
1) Go to the RealVNC Raspberry Pi sign up page and enter your email address in sign up box.
2) Follow the on-screen instructions to set up your account.
3) Back on your Raspberry Pi, click the VNC icon in the right corner of the screen to open VNC. Then click the status menu and select Licensing.
4) Enter your email address and password you created in step one. When prompted, select “Direct and cloud connectivity.” Your Raspberry Pi is now accessible online.
5)Download the VNC Viewer application on the computer you want to control the Raspberry Pi from, like the laptop or smartphone you’ll have when you travel.
6)Open the VNC Viewer application and enter the credentials you created in step one. Your Raspberry Pi will pop up as an option automatically. Select it to open up the connection. When prompted, enter your Raspberry Pi’s username and password (by default this is the username pi and password raspberry). Within a few second it’ll connect.
You’re now able to log into your Raspberry Pi’s graphic desktop from anywhere as long as your Raspberry Pi has internet access. This means you can take control of any security software, check on the status of any projects you’ve set up, or play Minecraft on your private server.
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You interconnect some networks so you must have a router and you have to configure it for example with static routes and/or a default gateway so it knows to what network it has to send addressed packets. If you do not have access to the router you can fake it with NAT (network address translation) so it means the raspi is on the same network. But this works only in one direction. You can also setup a VPN (virtual private network). With this you can safely connect through the internet from everywhere.