Well. That is true. But well known. Thanks anyway.

The problem with this is: It is good for ONE client behind a firewall. But when there are several of them it is hard to maintain.
And with DHCP nearly impossible.

And your aproach has the problem: If you have a dynamic external IP you have to readjust the force IP-option.

That should be done by this module on the fly.

Thanks again for your idea.
cu Dun3