Problem with configure Shaper machines with ProxMox 8 - Debian 12 LXC

[rudydevolder]

Debian 10 is deprecated and also the ProxMox version used in the examples. This makes that things are changes and

I don't seem to be able to get the IP-forwarding to work in the Shaper machines.

I am a newbie. Can someone give me the right direction?
The setup works when I replace my ShaperMachines with 3 virtual OpenWrt routers. But I would like to use the Shapermachines
instead.
I tried to create Debian VM's instead of LXC's and
in the examples everything that was marked "eth0" & "eth1" I replaced with "enp6s18" and "enp6s19" that I found to be present in my LXC machines.
And I also found IP-tables wasn't installed so I installed it, but all still to no avail.
If someone can gave me direction I could adapt the documentation for the installation ;)