Apps that target API Level 24 and above no longer trust user or admin-added CAs for secure connections, by default. Devices running Android Nougat offer the same standardized set of system CAsno device-specific customizations. The CA is safe and easy APIs to trust custom CAs to trust CAs. The CAs are also trusted by users for some domains, such as sensitive or sensitive content exchanged with the real server and not any user or administrator configured MiTMs. For confidential support call the Samaritans on 08457 90 90 90, visit a local Samaritans branch or click here.”]
Source: https://security.googleblog.com/2016/07/changes-to-trusted-certificate.html