Use Paket Filter with WAF

Hello,

I want to publish my SharePoint site collection for some of my external costumers.
I did this with WAF which worked well. However I am not able to restrict the access with paket filter. So everybody is able to connect to the website which my defined port to get the credential prompt of SharePoint.

I want to use to use the waf security features, so a simple dnat is not enough this time.
how can i handle that?

thanks for your help