I have a similar issue where the REST connector is failing intermittently and I did try with POSTMAN and it was getting successful and time taken is 108ms. However, with SOAP UI, I am getting the "SocketException" / "The API Key for this resource is missing or invalid" but never successful(Please refer Screenshots). I also verified Pega Logs and this error is not limited to one specific node,all the nodes are getting this error. How to debug/resolve this issue?
Connection reset simply means that a TCP RST was received. This happens when your peer receives data that it can't process, and there can be various reasons for that. The simplest is when you close the socket, and then write more data on the output stream. By closing the socket, you told your peer that you are done talking, and it can forget about your connection. When you send more data on that stream anyway, the peer rejects it with an RST to let you know it isn't listening.