Help to send data to thingspeak using MQTT+Arduino+Draginoshield v 1.4 through RAK 7249

Hello, can you help me?, I have an arduino with dragino shield v 1.4 with which I can currently send data through lora to my Thingspeak channel using a dragino 0LG01-N gateway, but I have not been able to do the same using a RAK7249. In the 0LG01-N it only has to be configured as: LoraRAW forward to the MQTT server, as I put in the server adress: mqtt.thingspeak.com and the server port: 1883, the frequency plan in 915000000
after that in the mqtt server setings tab I only select: thinspeakmqtt, and there I put my username, password client id credentials, below you can add the data of the local channel and the remote channel (which cannot be added in the RAK7249, or at least I don’t see where). Therefore after uploading my sketch to arduino (which if it works for 0LG01-N) it cannot connect to thingspeak to update the mqtt channel through RAK7249. specifically, could you help me send data from arduino with a dragino shield v.1.4 through lora to thingspeak’, thank you very much in advance.