I've had the same problem when trying to update to v11.25 - it either gets as far as "Downloading patch info from Highwinds CDN" or times out.
Here are the last few lines of the installer log:
0:00:00.011 D/WIZ: Starting installer... opening wizard step "Main Menu - Web Update"
0:00:00.033 I/DST: Updater selected installation /Volumes/EDD Hadfield/X-Plane 11/
0:00:02.836 D/WIZ: Advancing from wizard step "Welcome" to "Check Servers"
0:00:33.388 E/NET: Download failed with error: 28 for URL http://cds.n3w4x3c2.ssl.hwcdn.net/X-Plane%2011.25r2/directory.txt.zip
0:00:33.406 D/WIZ: Advancing from wizard step "Check Servers" to "Finish"