FileZilla is an FTP client that is commonly used to access files remotely. By default, the maximum number of simultaneous connections that you can have using FileZilla is 10. However, this can be changed by editing an XML file directly with a text editor. For the best results, we recommend that the maximum number of simultaneous connections is set to the same value on the server that you’re connecting to. Selecting 8 or lower and ending your FTP connection to the server once you are done connecting is highly suggested if you are receiving a 421 error….