Setting rDNS entries for Dedicated Servers is done via the Server Panel at https://server.ip-projects.de.
First Option:
Log in to the Server Panel with your account and navigate to Dedicated Server → Server.
In the overview, you will see all your Dedicated Servers.
Select the desired server and click on the IPv4 or IPv6 icon on the right-hand side.
A list of your assigned IP addresses will then appear.
Here, you can define an individual rDNS entry for each IPv4 or IPv6 address.
After making changes, save the entry by clicking the save icon to the right of the input field.
The procedure is identical for both IPv4 and IPv6.
Second Option:
Alternatively, you can manage rDNS entries through the Network → DNS section.
There, you will find the subcategories RDNS IPv4 PTR and RDNS IPv6 PTR, where you can also create or edit your reverse DNS entries.