same happens to me on every update and i have ports open. what i do is use utorrent to download the file.

1. install utorrent
2. start game update
3. stop game update
4. go to your Documents\My Games\FINAL FANTASY XIV\downloads\ffxiv\ folder. In my case i always have two folders there, one named 2d2a390f and 48eca647. Updates seem to fall on the second one.
5. go to 48eca647\metainfo and sort files by date modified.
6. check the newest and double click. should open in utorrent.
7. let it download the file (for that last update, mine took 16 mins after being stuck at 29% for 4 horus)
8. after you finish, go up one folder (from metainfo) and go to patch
9. copy the file that utorrent downloaded into the patch directory.
10. start the game again. this time the game should detect file and do a checkup, then starts installing

this has worked for me everytime