@Shekhar Nadide Thanks for reaching out. The term ‘Client Connection Failure’ essentially means that the client application (which initiated the API call) terminated the connection with the APIM service even before the backend API could revert with the expected response for the incoming API call and APIM could forward the same back to the client.
It basically implies that the client abandoned the request before the response could be received. APIM has no control over when or why the client decides to abandon the request. These failures generally occur when the request is taking too long to complete so the client either gives up (a user may close the browser) or the client application may have a time out.
please refer scenario3 in my blog for further information https://techcommunity.microsoft.com/t5/azure-paas-blog/troubleshooting-4xx-and-5xx-errors-with-azure-apim-services/ba-p/2115744
If you need further help, please share me the below details will check the backend logs.
Please email the following to AzCommunity@microsoft.com and we'll get back to you promptly: • Subject: "Attn: Janani " • Email body: Your Subscription ID, APIM instance name. • Email body: A link to this thread so we can validate and expedite the request
let me know in case of further queries, I would be happy to assist you.