I changed my SIM for another carrier and now it works.
I am in France, SFR is giving me 202 while it works fine with Orange.
Problem was default QNetworkRequest has an empty user agent, that my carrier proxy was blocking.
class UserAgentProvider : public QWebPage
explicit UserAgentProvider(QObject *parent = 0);
UserAgentProvider::UserAgentProvider(QObject *parent) :
userAgent = p.getUserAgent();