It’s a while ago since i had to deal with a phoenix controller, so i never tried to connect it to Ignition.
The error you are receiving is a little strange for a passive connection (0034h - Connection request was acknowledged negatively). A quick look to the manual shows that there is an timeout parameter in the connection string, that defaults to 500ms. My best guess is that once the FB is enabled it waits 500ms for the active partner to establish a connection and then fails with the above message. Can you see a 500 ms delay between fb activation and error when monitoring the online status?
To make sure the port is really opened on the controller you can try a simple telnet connection (on windows: telnet 10.28.20.54 47000).