I'd like to know why i keep loosing signal on my air 2s when i do waypoints ?

The waypoints in the DJI Fly App for the Air 2S are limited to the Hyperlapse feature.  

You need to take a look at a 3rd party APP like Litchi for actual waypoint missions.

Hello there sala. I am sorry for the trouble this has caused and thank you for reaching out. May we please know if you are receiving any error message or any error codes on the DJI Fly application and may also please know what is the model of the mobile device that you are using please for us to be able to isolate the issue? Thank you.