I couldn’t find TcpKeepAlive for node.js. It’s definitely there for Java and .Net SDKs client settings. In node.js 2.6 sdk you could specify some timeout settings for operations.
https://docs.couchbase.com/nodejs-sdk/2.6/client-settings.html.
The 201 error is coming from the libcouchbase C library, so enabling logging for the app might be the best route to troubleshoot the issue.
https://docs.couchbase.com/nodejs-sdk/2.6/handling-error-sample-code.html#monitoring