Why I have slow FTP download speeds

FTP is one of the most common methods used for transferring files from a remote server to your computer. FTP transfer can have an ideal experience if FTP speeds are maximized but that is not always the case.In this guide, we will provide all the information needed so that you can troubleshoot your problems and find optimal solutions, and use most of your resources for better speed performance.

Table of Contents:

  1. Possible speed limitations:
    1. FTP speeds metrics
    2. Network Bandwidth limitations
    3. Network hardware limitations
    4. Testing FTP speeds
  2. FTP working mechanism and protocols:
    1. How FTP works?
    2. Alternative to FTP protocol
  3. Configuring your FTP client for maximum speed 
    1. Concurrent Downloads
    2. Segmented Downloads
    3. Other settings which can improve FTP speeds
  4. Troubleshooting slow FTP speed
    1. Verifying network
    2. Using wired connection vs Wireless network
    3. Checking your Firewall

  1. Possible Speed limitationsYour network bandwidth is the most important factor which determines your FTP speed. Knowing your network bandwidth would enable you to understand the network resources available at your end.
    • FTP Speeds metrics:Your ISP may have provided your bandwidth in terms of MB/s or Mib/s which have different meanings. So let’s first get our speeds metrics understanding right. We will use 1 Mbps (Megabits per second) as the base unit.
  • One Mbps = 1000 Kbps (Kilobits per second). 
  • 1 Mbps = 125 KB/s (Kilobytes per second).
  • One Mbps = 976.5 KiB/s (Kibibites per second). 
  • 1 Mbps = 122.07 KiB / s (Kibibytes per second). 
  • One Mbps = 0.953674 Mib/s (Mebibites per second).
  • 1 Mbps = 0.125 MB/s (Megabytes per second).

    • Network bandwidth Limitations: Most ISPs advertise their Internet download speeds in Mbps. While it is technically correct, it confuses many consumers, because their testing tools display other metrics. Some ISPs also advertise only their asymmetrical speeds. They show how incredible their download speeds are but don’t mention the upload speeds, which sometimes are 3x slower. To know your real bandwidth, measure it using online testing tools. You can use tools like ookla speed test which provides you all the details from your upload speed to download speed and also the correct speed metric used for measuring your speed.
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    • Network Hardware Limitations: Your Local machine’s limitations - A computer with low CPU and ram memory can result in slower FTP speeds but a high-end computer with average network bandwidth also doesn’t give encouraging speeds. Wi-Fi connections are slower due to packet loss and delay. Wi-Fi protocols like 802.11n support high-speed bandwidth up to 300 Mbps but they are not ideal choice for constant uploading and downloading.
    • Testing your FTP download speeds: You can test your FTP download speeds using popular free-to-use tools like Tele2Speedtest. This service allows you to test both the upload and download speed through your FTP client without providing a username and password.
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  1. FTP working mechanism and protocols:
    1. How FTP works?FTP works as a basic server/client protocol. In simple words, a network connection enables you to send and receive files with each other. It uses the TCP/IP protocol model for communication and for file transfer. It uses port number 21 for creating connections but the downside of FTP is that it doesn’t provide encryption.The FTP Client provides: 
  • Seedbox Login credentials.
  • FTP commands. 
  • browse directory

The FTP Server provides

  • Authentication.
  • Directory display
  • Port assignment.

Let’s understand the functionality of FTP keeping seedbox in mind:

  1. Your seedbox provides credentials and IP or hostname to access your seedbox (FTP server) remotely from your computer (FTP client)
  2. You log in remotely into your seedbox from your computer.
  3. From your seedbox you can download files as the FTP server in your seedbox provides authentication and assign port numbers (21,22).
  4.  You can now use your FTP client as an interface to connect to your FTP server as it takes login credentials, sends FTP commands, and browses through the file directory.


  1. Alternatives to FTP:Apart from FTP, there are many other protocols and applications which provide much better security and file transfer speeds compared to FTP. A protocol like SFTP(SSH File Transfer Protocol) works through SSH and provides much better security over FTP. HTTP and HTTPS provide much faster speeds along with good security features which makes it a good alternative to FTP as a whole.
  2. FTP vs SFTPThe main difference between the two protocols (FTPS and SFTP) is their way of functioning. There is a performance overhead on FTPS since it needs multiple ports. For every new transfer file is requested, FTPS requires a new port for the data channel. The upside of this is that the control and data channels run asynchronously in two different connections; this exclusive data channel makes transfers much faster. While the  SFTP needs one port number for all communication to the data channels, making it much easier to secure and with less performance overhead. But having the same channel for control and data can turn out to be a bit slower.
  3. Configuring your FTP client for maximum speed
    1. Concurrent Downloads:The concurrent download is a technical concept where it gives the ability to download multiple files simultaneously at the same time using FTP. FTP applications that support this feature create multiple connections to the server for downloading. It is very beneficial when someone is trying to download a folder of files. Let’s assume that  there is a session bandwidth limitation then creating multiple connections will eventually exceed the provided per session speed which will result in an overall improvement in download speed.Free to use FTP clients which provide concurrent downloads are – FileZilla
    2. Segmented Downloads:A fragmented download is actually a file transfer concept where a large file at the sender end is broken into fragments or pieces and these pieces are sent to the receiver through multiple FTP connections and at the receiver’s end these pieces are recombined to produce the original file.In this FTP transfer technique fragments of a single file are downloaded simultaneously through multiple FTP connections and after downloading these fragments these are recombined to create the original file.Free to use FTP apps that provide this capability are: BitKinex, CuteFTP Pro, Progressive Downloader (MAC)
    3. Other settings which can improve FTP speedsFTP Speed limits: Please make sure that your FTP client does not have any download/upload speed limits. FTP active and passive mode: If your FTP is hosted with NAT( proxy or VPN), the FTP Passive mode should be configured. The passive mode seems to be slower than active.
  4. Let’s verify the network Loss of packets within the network can also contribute to slower FTP  speeds.
  5. Ping the local gateway

Updated 30 Apr 2021
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