I only used GNS3 and Cisco Packet Tracer from the list when self-teaching CCNA. GNS3 installation shouldn’t be that hard. On Windows just use the installation and fire up a VM in VBOX / HyperV (recommended) and it should automatically detect it. On Linux I have installed GNS3 using AUR package in ArchLinux, haven’t tried on Ubuntu, but it should be straight forward. For the VM, you will need hypervisor setup (virt-manager, libvirtd) and KVM enabled. Most of the distrobutions should have its own kvm virtualization guide. You can also skip GNS3 installation on the host and just go to IP of the VM,so you can use beta Web UI where you can do most of the things you can do in GNS3 app. Good luck!

Nope it just doesn’t support it. I tinkered a bit in router config enabling IPv4/IPv6. But didn’t get IPv6 address from ISP. Still using ADSL2+

So, I can receive incoming traffic using IPv6 despite I don’t even have a public ip? (nv my ISP doesn’t support IPv6)

I cannot acquire a public ip on the top right, it is nearly impossible. Forwarded traffic will mostly be straight TCP and UDP traffic. The server at the top left must only forward all traffics to top right network somehow. It should not modify anything. I just need to make use of that public ip from my private network.

Thanks for the reply! I will research it a bit, I still lack tons of knowledge about networking, yet still learning.

I don’t think double NAT is my case. My ISP doesn’t provide me with a public IP.

Excuse my amateur drawing…

I barely got my username with one character change.