As of July 2025, Flutter apps ignore proxy settings. As a result, HTTP/WebSocket communication from Flutter's Dart VM currently cannot go through a user fixed IP. Instead, the communication originates from the IP ranges 207.254.20.32/27 and 207.254.59.128/25. As a temporary workaround, it is necessary to allow traffic from these IP ranges. For more details, please refer to this page.
Additionally, for the same reason, it is not possible to run tests against private environments using MagicPod Connect.
If you would like support for Flutter apps with user fixed IPs, please vote below.