Issue with SSL Certificate

[Hulkewi]

I'm using a Web API .NET core application (Server side) and a Xamarin application (Client side).
When i try to connect my mobile application to the Web API Url , i have a SSL Certificate problem , i even tried to bypass the certificate but still the same problem.
FYI : I can access the URL with the browser on the device
If there is any solution please !
Thanks