We are receiving a certificate error when trying to log in our site via Moodle App: we type the site name/URL and when we tap on the site the app returns this certificate error:
 
The certificate of this site cannot be trusted by your device: TLS connection could not be established: javax.net.ssl.SSLHandshakeException: Unacceptable certificate: CN=AAA Certificate Services, O=Comodo CA Limited, L=Salford, ST=Greater Manchester, C=GB
 
There is no problem when logging in with web browsers (we've tried with several browsers, both computer and mobile versions), and the certificate is valid until January (just in case I've rechecked it on https://www.geocerts.com/ssl-checker and https://www.ssllabs.com/ssltest/ and they give no error).