My educated guess at the problem is that the Phasor is providing "gibberish" (e.g., containing special characters)for the queue name. FFCore cannot "accept" the queue name and displays a misleading error message. Xerox support for the Phasor should confirm (and fix if necessary) that the queue name communicated by the Phasor is valid. You should also try Xerox support for FFCore -- may not be too helpful as the Phasor is not on the supported printer list for FFCore.
We can ping the printer from the FFCore server. It is also installed as a network printer at the FFCore server and I was able to print a test page from the FFCore server. When I try and define this as a printer destination the Printer Queue Name populates with a strange string of charactors which include diamond with question marks symbols, not what would be expected. Then when I hit Save I get the invalid IP or DNS message.
The Phasor is not officially supported by FreeFlow Core (it can still work). Can you ping the Phaser from the FFCore server? Are you able to connect to other printers with the FFCore? I am suspicious that the Phaser's IP has changed and hence the dropped connection at FFCore.
I understand your frustration with the inability to attach pictures.
I can no longer connect to my Phaser 7800DN with Freeflow Core after having a board replaced by Xerox Tech. I keep getting a message telling me Printer DNS Name or IP Address are invalid.
I would insert a pic of the message but Xerox form is like theonly form on earth which doesn't have this ability