With due respect. Change with “firewall_backend = “iptables”” didn’t work for me, was one of the first things I checked.
I did however found ONE topic which suggests to use “virtio-net” Host: Manjaro, Guest: Artix Linux, Issue: No virtio NAT connection on VM (KVM, qemu, libvirt, virt-manager, connman) - #8 by Teo which appears to be working for me. So I guess I had to dig slightly below the surface, as I don’t see it mentioned in this topic.
No need to be so dismissive just because I have like 4 posts on forums, I can read pinned threads 
(PS: There’s a slight difference between completely lacking the connection and having the connection degraded)