When a non-internet connected LAN is enabled QWebEngine's loading of external resources over HTTP, <img> or <script> tags for example, is extremely slow ( >3 seconds per resource).
Steps to reproduce:
1. Connect to the internet
2. Connect an additional LAN (second laptop with no internet connection)
3. Build and run the NanoBrowser example app
Disabling/Enabling the LAN instantly fixes/reproduces the issue.