FTP Error 421 Too Many Connections From This IP: Causes and Fixes for Pure-FTPd, ProFTPD and vsftpd

Updated: 8 October 2026 · Applies to: Pure-FTPd 1.0.50, ProFTPD 1.3.8c and vsftpd 3.0.5 on Debian 13 (tested); cPanel and WHM 112 and later (from cPanel documentation)

FTP error 421 "Too many connections from this IP" means the FTP server already has as many connections from your IP address as it allows, so it refuses the next one. On the client side, use fewer simultaneous connections and close old sessions. On the server, raise the per-IP limit: MaxClientsPerIP in Pure-FTPd, MaxClientsPerHost in ProFTPD or max_per_ip in vsftpd. On a cPanel server running Pure-FTPd, use Maximum Connections Per IP Address in WHM's FTP Server Configuration.

Which server sent the message

Each FTP server words its refusal differently, and each has a per-IP limit and a total limit. We ran all three with low limits and opened connections from one address until they refused:

• Pure-FTPd (also used by Centova Cast and SonicPanel), per IP: 421 Too many connections (2) from this IP. Total: 421 3 users (the maximum) are already logged in, sorry. The per-IP refusal came straight after connecting, before the login.
• vsftpd, per IP: 421 There are too many connections from your internet address. Total: 421 There are too many connected users, please try later.
• ProFTPD answered with code 530 at login, not 421, in our test with its default messages: 530 Sorry, the maximum number of clients (2) from your host are already connected. Total: 530 Sorry, the maximum number of allowed clients (3) are already connected.

The number in brackets is the server's setting, not your connection count. A per-IP refusal is about you (or everyone behind your router); a total refusal means the server is full, and only waiting or a higher total limit helps. cPanel servers use Pure-FTPd or ProFTPD, chosen in WHM under Service Configuration > FTP Server Selection.

Fix it on the client

• Lower the number of simultaneous transfers. FileZilla runs two transfers plus a browsing connection by default; FileZilla error 421 Too many connections (2) shows the exact settings.
• Disconnect extra tabs and other FTP programs, and remember that colleagues behind the same office router share your IP address.
• Wait for stale sessions to time out, then reconnect. Defaults: 15 minutes on Pure-FTPd, 300 seconds (idle_session_timeout) on vsftpd.
• Scripts using curl may report this refusal as a timeout. Against our Pure-FTPd, curl -v showed:

  < 421 Too many connections (2) from this IP
  * We got a 421 - timeout
  * closing connection #0
  curl: (28) Timeout was reached

Raise the limit on the server

cPanel and WHM: go to Service Configuration > FTP Server Configuration. According to cPanel, Pure-FTPd offers Maximum Connections Per IP Address, Maximum Connections (server-wide) and Maximum Idle Time (minutes). For ProFTPD, WHM offers only Maximum Number of FTP Processes, which limits total connections because each connection is one process, and Maximum Idle Time (seconds). Click Save.

Pure-FTPd in a configuration file (we tested these names):

MaxClientsPerIP     4
MaxClientsNumber    50

On the command line the same options are -C (per IP) and -c (total, default 50). Debian and Ubuntu packages start Pure-FTPd through a wrapper that reads one file per option instead:

echo 4 > /etc/pure-ftpd/conf/MaxClientsPerIP

Restart Pure-FTPd afterwards.

ProFTPD, in proftpd.conf, then check the syntax with proftpd -t and restart:

MaxClientsPerHost   4
MaxClients          50

ProFTPD also has MaxClientsPerUser (530 Sorry, the maximum number of clients (2) for this user are already connected.) and MaxConnectionsPerHost, which refuses before login.

vsftpd, in vsftpd.conf, then restart:

max_per_ip=4
max_clients=50

According to the vsftpd manual, both work only in standalone mode (listen=YES or listen_ipv6=YES). See also vsftpd key settings.

Centova Cast: its FTP server has its own configuration; follow increasing the maximum FTP connections per IP in Centova Cast.

Raise the limit a little at a time. The Pure-FTPd manual calls the per-IP limit a very effective way to prevent denial of service and bandwidth starvation by a single user.

Hosted accounts

On a hosted account (Ucartz shared, reseller or radio hosting) the limit is part of the server's configuration, so you cannot change it yourself. Apply the client fixes first; if you still need more connections, open a support ticket. Server management for your own server is available through Ucartz server management.

Official documentation: cPanel: FTP Server Configuration, pure-ftpd(8) and vsftpd.conf(5).