The Phoenix were keen to acquire the talented former Socceroo after he completed his initial contract at Hartlepool. However, the club exercised an unusual option in Porter's deal to secure his services for another season.
Phoenix chief executive Tony Pignata was disappointed to have missed out on bringing Porter to Wellington but said the club would step up efforts to lock in some other promising player.
"Joel's a quality striker and would have fitted in well with the squad. But the situation had really gone on for a lot longer than we were comfortable with and we made the decision to move on," he said.
"We have been looking at our options with regards to strikers during talks with Joel and Hartlepool and getting him to sign on as well would have been a huge bonus."
The Phoenix are seeking a proven scorer to complement season one star Shane Smeltz.
While Porter is off the radar this season, Pignata said the door would remain open for the Australian to link with the Wellington club when his contract at Hartlepool ended.