i have a zyxel usg40 , that should protect my network from virus [ but it never found any in a year...even no cookies..] and be a firewall .
tixati is not able to open its port correctly , while if i use utoorent or qbittorent , they do it well .
here is a screen capture showing them well registered as upnp and tixati's port not...

(Pic removed by Mod)

Same problem reported by multiple users, all concerning the latest builds (posterior to 2.12, on which UPNP was working for the same users):

http://forum.tixati.com/support/1705/

try the alpha, much work has been done.

http://testing.tixati.com

I had the same problem, seems fixed now with the new version 2.18 . Try upgrading, jcgeny.