Timeout connecting to iot core service in k8s pod

[ZhangPengPaul]

software.amazon.awssdk.core.exception.SdkClientException: connection timed out: *******.ats.iot.cn-north-1.amazonaws.com.cn/...:443

I have set up the JVM's dns cache as provided at https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/jvm-ttl-dns.html, but it did not take effect

Can someone tell me if there's anything else I might be missing?