Hello,
This is the second time I've run into this problem and I find it basically inexcusable. When VCSA takes a backup over FTP it tries to make a seemingly unlimited number of FTP connections simultaneously for a reason that I cannot discern.
So if you have your FTP daemon configured to limit the number of connections per user the backups fail.
Please fix it so that it uses a published/defined number of connections and for god's sake make it user configurable.