Rangers boss Stuart McCall says he feels sorry for Gael Bigirimana, but admits he should never have been signed.
Chris Gunter will stay at Reading, after the club took up the option to extend his deal by another year.
The 27-year-old first moved to the Bundesliga side on loan in January 2013, with the deal extended for this season.
Djourou, who came through the Arsenal youth system, would be keen to stay on.
"I know the coach, I love the club, I love the city. HSV (Hamburg) is incredible," Djourou said in German newspaper Bild.
"The club has so much potential. We have to go way up.
"The fans are great. The mood is different than in England. If all goes well and the club also want to, I would stay."