Comment 4 for bug 1626501

Useing Wireshark I can see the problem. Both XMLHttpRequest and wget do not allow you to change the User-Agent by simply setting the header with that name.
Wireshark shows that QT's XMLHttpRequest is using 'User-Agent: Mozilla/5.0'. The https://linuxgamecast.com/feed/lwdwmp3/ site is explicitly no accepting this (lovely)! This can be reproduced with:
wget --user-agent=Mozilla/5.0 https://linuxgamecast.com/feed/lwdwmp3/

One workaround would be to set a more 'acceptable' User-Agent. What that would be for all sites is anyones guess! The User-Agent cannot be set directly in 'XMLHttpRequest' see:
  https://bugreports.qt.io/browse/QTBUG-20473

This mentions: Implementing a custom QNetworkAccessManager and setting the header there solves the problem