Thank you for that really fast reply.
Ok, I found the previous configured in the Static discovery tab, thank you for that hint.
But now, even after I did restore the addresses manually, the iSCSI volume does not get connected in ESXi.
After testing a little, the volumes now disappeared in ESXi, but the iSCSI device is still there.
When trying to "add new storage" I see the device, but when trying to find the partition table,
ESXi says "Loading..." and does not find anything for a long time... ???