Neptune Jupyter Notebook Connection Error

I met the following error when running this in the Neptune jupyter notebook. What is strange is that I CAN connect to the Neptune with the same jupyter notebook this morning and yesterday, but now I can not.

%oc_status

{'error': ConnectionError(MaxRetryError("HTTPSConnectionPool(host='sg-plat03-infra-atlas-demo.cluster-cvuttnfmjjlx.ap-southeast-1.neptune.amazonaws.com', port=8182): Max retries exceeded with url: /openCypher/status (Caused by NewConnectionError('<urllib3.connection.HTTPSConnection object at 0x7f5265b62a50>: Failed to establish a new connection: [Errno -2] Name or service not known'))"))}

I tried run some nslookup command in the jupyter notebook instance and it didn't work

nslookup amazonaws.com
;; connection timed out; no servers could be reached
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