The Black Cats had been interested in signing the Dutch international during the summer transfer window, but no move materialised, with the deal collapsing at the last minute over fitness issues.
“That’s a closed book now in regards to Sunderland. I’m here at QPR and I’m happy and focused for the rest of the season," he said.
“Even if I have left the club then, it was only on loan, so I still would have been a QPR player at the end of the day.
“I stayed here and didn’t play for a few weeks, but as I said that’s all over now and I just want us to crack on and put a winning run together and hopefully get back into the Premier League.”
Fer’s form will be crucial to QPR’s chances this season, as he is such a key player for Chris Ramsey’s side.
The 25-year-old’s ability makes him one of the standout players in the Championship, and getting him back to his best will be crucial if the R’s want to achieve promotion this term.
So far Fer has missed much of the season through injury, restricting him to just five appearances.
The former Norwich City man will be hoping to make an impression at the weekend, though, when QPR take on local rivals Brentford on Friday evening.