[throw501]

workaround if you don't need IP6:

System Preferences > Network > [click your ethernet or wifi adapter on left, unlock padlock if needed] > Click Advanced on right > Click TCP/IP tab > NONE, or Configure IPv6: Link-local only

[yoz-y]

I actually already have this setting enabled. But it will still give you an ipv6 address and even though I do have a local ipv4 address on this interface, the application will pick up the ipv6.

The problem seems to come from the fact that the port is just appended to the address, but with an ipv6 you have to surround it with brackets

    [1::c0de:f0r::f00d]:1337

[tmuir]

what exactly am I giving up, by doing this?

[voxadam]

IPv6