qubesos 4.2 switched from iptables to nftables and afaik qubes-tunnel isn't updated yet.
https://forum.qubes-os.org/t/can-t-get-the-qubesos-contrib-qubes-tunnel-to-work-in-4-2/22054
the setup i mentioned is much simpler and works on 4.2. lmk how you go with the Fedora template