How to make a WAF rule

Hey there.
Does anyone know how to make a general WAF rule that will show captcha to all direct traffic who use Android?

Hello!

Create a rule with this expression:

(http.user_agent contains “Android” and not http.referer contains “https://youwebsite.xyz”) or (http.user_agent contains “android” and not http.referer contains “https://youwebsite.xyz”)

Change https://youwebsite.xyz to your website.

Then select Managed Challenge or Interactive Challenge.