For the configuration of eduroam use the mobile configuration profile eduroam_2018.mobileconfig from the website of the ZDV.
Manual configuration is not supported. The profile can be used as of iOS 6.
Please check at Settings → General → Profiles if there is an eduroam profile installed. If so, delete this profile.
Download the profile eduroam_2018.mobileconfig. The profile is displayed. Touch "Install".
In the next screen, tap "Install" to add the T-TeleSec_GlobalRoot_Class_2 certificate to the trusted certificates.
Enter your login ID as <ZDV login ID>@uni-tuebingen.de. Enter your password. Touch "Install" again.
Now you are ready to use eduroam Wi-Fi.