Thanks for the software! I am learning.
I was following this guide whonix(.)org/wiki/KVM#Arch_Linux (I am running CachyOS)
Things were going great, but then I ran into some trouble with Whonix Gateway not having a working wired connection → no Internet.
I tested with another VM and soon realized that the problem persisted, having nothing to do with Whonix, but rather my QEMU/KVM with virt-manager setup.
It has taken embarrassingly long to solve this problem. You should consider incorporating some of the following into your wiki. Perhaps here whonix(.)org/wiki/Troubleshooting#Connectivity_Troubleshooting
From what I gather this problem has affected Arch users since the libvirt-1:10.4.0 update.
You need to set
firewall_backend = "iptables" in /etc/libvirt/network.conf
Then
$ sudo systemctl restart libvirtd
I hope this helps. More here reddit(.)com/r/archlinux/comments/1d9dsyy/last_update_broke_virtual_networking/