Hello @krishna parajuli,
welcome to this moderated Azure community forum.
I'm not sure why this should not work anymore, it seems there is no general outage on the IoT Hub.
Please check this blog post why this is not the best node-red device client.
A better node was introduced later. Can you check with this node?
Otherwise, test the connection with eg. Python to double check the connection.
If this does not work, consider creating an Azure support ticket.
If the response helped, do "Accept Answer". If it doesn't work, please let us know the progress. All community members with similar issues will benefit by doing so. Your contribution is highly appreciated.