The 32-year-old has signed a one-year contract with the Red Shorts, who are looking to get back into the Bundesliga at the third attempt.
Despite only rejoining the club last summer and having a contract until 2023, Zieler was unceremoniously told he would play no further part in Kenan Kocak’s plans in the upcoming season.
He will spend the next season at the HDI-Arena having fallen out of favour under current Effzeh coach Markus Gisdol.
Hannover 96’s hopes of bringing back Jannes Horn on loan for a second season appear to have been ended by his parent club 1. FC Köln.
Marvin Rittmüller has become the second signing of the summer at 1. FC Heidenheim, joining on a free transfer from Köln II.
SSV Jahn Regensburg have made their first signing of the summer, bringing in striker Kaan Caliskaner from 1. FC Köln.