Trust Anchor for Certification path not found - https POST Request with Volley not working - android-volley

Question

this question is asked very often, but all the answers 2 or 3 years old. I have a login for my Android app and the date is saved in a MySQL database on my cloud server which has a SSL certificate.
When I test my app on my local machine everything is fine, but when I try to connect with my cloud server I get the message "Trust Anchor for Certification path not found". My credentials are ok.
I know that I have to set a sslSocketFactory. I tried so many, but one worked. I´m sitting now for days. May someone had a idea how to solve
here my code without sslSocketFactory
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.logintest, container, false);
btn_login = view.findViewById(R.id.btn_logintest);
email = view.findViewById(R.id.etEmail);
password = view.findViewById(R.id.etPassword);
btn_login.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
login();
}
public void login() {
str_email = email.getText().toString();
str_password = password.getText().toString();
if(!str_email.equals("") && !str_password.equals("")) {
StringRequest request = new StringRequest(Request.Method.POST, URL_LOGIN, new Response.Listener<String>() {
#Override
public void onResponse(String response) {
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction= fragmentManager.beginTransaction();
DummyFragment dummyFragment = new DummyFragment();
fragmentTransaction.replace(R.id.container,dummyFragment);
fragmentTransaction.addToBackStack(null);
fragmentTransaction.commit();
Log.e("Text: ", response);
Toast.makeText(getActivity(), "erfolgreicher Text: " +response, Toast.LENGTH_LONG).show();
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
Toast.makeText(getActivity(), "Text: " +error.getMessage().toString(), Toast.LENGTH_SHORT).show();
}
}
) {
#Override
protected Map<String, String> getParams() throws AuthFailureError {
Map<String, String> params = new HashMap<>();
params.put("str_email", email.getText().toString());
params.put("str_password", password.getText().toString());
return params;
}
#Override
public Map<String, String> getHeaders() throws AuthFailureError {
try {
HashMap<String, String> headers = new HashMap<>();
String credentials = "xxxxxxxxx:xxxxxxxxxx";
String auth = "Basic "
+ Base64.encodeToString(credentials.getBytes(), Base64.NO_WRAP);
headers.put("Content-Type", "application/json");
headers.put("Authorization", auth);
return headers;
} catch (Exception e) {
Log.e(TAG, "Authentication failure");
Toast.makeText(getActivity(), "" +e, Toast.LENGTH_LONG).show();
}
return super.getHeaders();
}
};
RequestQueue requestQueue = Volley.newRequestQueue(getActivity().getApplicationContext());
requestQueue.add(request);
}
else {
if (email.getText().toString().equals("")) {
Toast.makeText(getActivity(), "Bitte Email Adresse eingeben", Toast.LENGTH_SHORT).show();
} else if (password.getText().toString().equals("")) {
Toast.makeText(getActivity(), "Bitte Passwort eingeben", Toast.LENGTH_SHORT).show();
}
}
}
});
return view;
}
}
I tried the code from android developer page, but some error. I tried to set network_security.xml but it didn't worked for me. When I test my credentials with postman I get response 200.