Mathias: are you after using a separate (different) proxy server just for U1 uploads/downloads, or does u1sync-daemon just need to use the system-wide configured proxy server (eg. in GNOME).
Mathias: are you after using a separate (different) proxy server just for U1 uploads/downloads, or does u1sync-daemon just need to use the system-wide configured proxy server (eg. in GNOME).