Unable to add devices

Hi, We had difficulties to make chirpstake v4 running on linux mint to see our gateway (IOT Femto Gateway (model name: WLRGFM-100)). After following the recommedation to uncomment topic_prefix =“eu868” in eu868.toml (Connecting Dragino Lig16 gateway to chirpstack server) the gateway is online in chirpstake, but we are not able to add devices (Dragino Soil Sensor LSE01-8). We followed Connecting a device - ChirpStack open-source LoRaWAN® Network Server documentation, but LoRaWAN frames on the device page (Tenants/ChirpStack/Applications/ Sensors/Devices/Sensor_001) remain empty. OTTA key is set correctly and Join Requests are received. I assume that his has to do with mentioned uncommenting. Anyone any idea what to do?

=> Problem solved: The devices need to be restarted > The device on Chirpstack can't reconnect after I try to connect the device to the TTN Server