So the problem is as the title states - Tixati always reports that the selected port is closed. I've never had this problem before with Tixati and I have no idea what triggered it (it's not that it appeared just after last update).
I know sure that the default port 13728 is open and µTorrent for example also reports that. But Tixati doesn't and since yesterday always fails to connect with any peers/seeders and always brings up the annoying message box that the post is closed. Tried changing to port 1035 which should (also) work but still problems. Although Tixati succeeds in connecting with peers/seeders (and downloading/uploading) when using port 1035, it still constantly brings up the annoying message box that the port is closed.
Like I said, no idea what triggered this but it's really annoying and really strange IMO that Tixati can't use port 13728 anymore and that it always reports that the port is closed (doesn't matter which port I try and even if it works with the selected port, the annoying message always keeps popping up)

I still have the problem and it also happens when connecting to other networks!
"Could not listen for incoming connections, Address: :::1035/0.0.0.0:1035, Error: Bad access"
Downloading and uploading still works but I can't really use Tixati if the annoying error message keeps popping up every x seconds (at least once a minute)

Will uninstall v1.96 and try one of the previous versions

If you mean the "Incoming TCP Connections Port Bind Error" as it is described in help topic, this error is not caused by closed port, but some other program that use the same port as Tixati. Remember when this error started to appear and see what programs where installed at that time. Maybe this way you will be able to find the cause of this problem.

Yes, that error, thanks for your answer.
I've just exported all transfers, uninstalled the whole thing and reinstalled v1.95. After that exported all settings (incl default network settings), uninstalled v1.95 and reinstalled v1.96. Imported all settings and problem hasn't appeared again (using port 23355 now). Still no idea what caused the problem (I did try using 3 alternative ports which all should've been open and µTorrent was on a different port) but the error hasn't shown up again so I'm happy :)