I can control the network for the whole device with Network Link Conditioner but is there a way to do it just for selected hosts? I know that with /etc/hosts I can totally block connection to a host, but it's not what I need here. As a minimum solution, if I were able to make a host never respond, but just keeps loading forever, it would work, too.
I make a VM when I need this and only install the conditioner on the VM. It’s usually no hassle for me to have the entire computer slow or lossy when I’m testing and then I return it to full performance when I’m done.
I suppose it depends on why you are wanting to have differential speeds out of the same network interface. It’s really a lot of complexity to poke holes in the filter when it’s implemented on a per interface basis. I’m curious what your use case is for not just doing the testing and returning your network interface to full speed.