I created a Gateway with the correct Gateway EUI on eu1.cloud.thethings.network successfully, than I resettet my TTIG-868 and configured WLAN new. but in console it is shown as disconnected.
If you had used search before posting you would see this has been addressed multiple times in the last coupe of weeks. TTIG needs a V3 CUPS so not yet ready for migration, stick with V2 for now, until released. We will post to the forum once migration of TTIG viable.