Qt Android App can't connect to internet via XMLHttpRequest

Hi there,
This is a strange habit that I have no clue how to fix it. Here's what happen.
- Qt android app 's written and everything works on one phone/tablet but
not on the others.
- It works on android phone/tablet version 5 (lollipop) but seemingly not on
android version 6 (marshmallow).
- What's not working is the part that I read JSON data from Thingspeak
using JavaScript's XMLHttpRequest. As mentioned above, it works perfectly
on one phone/tablet but not on the others.
- The only clue I have on the not-working phone/tablet is this
qt.network.ssl: QSslSocket: cannot resolve CRYPTO_free
qt.network.ssl: QSslSocket: cannot resolve EVP_rc2_cbc
qt.network.ssl: QSslSocket: cannot resolve SSLv2_client_method
qt.network.ssl: QSslSocket: cannot resolve SSLv2_server_method
qt.network.ssl: QSslSocket: cannot resolve EC_get_builtin_curves
qt.network.ssl: QSslSocket: cannot resolve EC_curve_nist2nid
qt.network.ssl: QSslSocket: cannot call unresolved function EC_get_builtin_curves
qt.network.ssl: QSslSocket: cannot call unresolved function EC_get_builtin_curves

- hence, reading JSON part gave "JSON.parse: Parse error"

- Any help would be appreciated...

:D:D:D