Eg, Too many connections (10) from this IP: [xx.xx.xx.xx]
The reason you got this is our Linux server allow only 8 connection from 1 IP.
To resolve this issue, you may use the following step to set the similtaneously connectoin to 1 only.
1. Launch your FileZilla FTP Client.
2. Select on Edit and hit on Settings...
3. Click on Transfers from the "Select page:" panel.
4. Change the value of Maximum simultaneous transfer to 1 only where the original value is 5.