Problem solved. I created a new keystore(JKS format) for OpenFire with Key Store Explorer.
I added to the keystore the complete path of root and intermediate CA to the domain validated certificate.
(AddTrustExternalCARoot, USERTrustRSAAddTrustCA, SSLcomDVCA_2).
I also added these three certificated to the trusted CA of Android (Only AddTrustExternalCARoot was already present).