I have set up ODK Central successfully using a custom SSL Certificate. I am however still receiving the error Cannot securely connect to the Server when I try and sync from ODK Collect. My URL is https://central.zema.org.zm
Your intermediate certificates are not installed properly. See https://www.sslshopper.com/SSL-CHECKER.HTML#hostname=central.zema.org.zm for how to fix it.
Thanks for the suggestion, I looked into the SSL and Rectified the issue.