Very interesting. I'm in the same boat. I just recently bought a Time Capsule 3TB. I have a 2014 Macbook Pro Retina and wanted to update a Godaddy website in Muse. When I try to publish to Godaddy using this specific network it will stop at 68% or when the logging into FTP message on the bottom appears. If I use another network it will work fine.
I called Apple and they have no solution. From my basic research I found Muse uses TCP UDP port 6888 and unblocking them seems to not work in Airport.
Any ideas?