Idle FTP connections are triggered when an FTP client opens multiple connections, without closing the previous ones, or due to an incorrect setting. If your FTP client is using more than 8 connections at the same time, you will get refused with a message similar to this:
Response: 421 Too many connections (8) from this IP Error: Could not connect to serverIf you encounter this error, you will need to close the idle FTP connections in cPanel. To do so:
1. Login to cPanel.
2. Under the heading Files, click FTP Connections.