There are 3 things you should check
- Check if your cluster has been configured as a Private Cluster. If so, you'll need to be on the same network.
- Check to see if your cluster has been configured with IP Whitelisting. If so, you'll need to ensure your source IP is in the list
- Ensure the cluster is healthy by looking at the service in the Azure Portal. Explore the troubleshooting options inside the service blades in the portal to pinpoint.