Ubuntu run multiple instances of AppImage using Network Namespace isolation [closed]

I have an AppImage which I need to run 3 instances of, concurrently. Each instance will use it's own profile (Home directory). That's all very easy:

HOME=/home/user/home AppName.appimage

Now the trouble is that this app open two network ports. Hence, when I try to run instance number-2 it fails, because the said ports are already in use, by instance-1.

As per my research, I think I can create network namespace isolation. Where each isolation is able to connect to the internet, but is disconnected from each other.

Would appreciate if someone can help guide me and advise how to set it up

PS: using docker or VM will not be viable.