pure-ftp 50 users (the maximum) are already logged in, sorry

ISP 3.
i have this error:
Risposta: 421 50 users (the maximum) are already logged in, sorry
11:21:55 Errore: Impossibile collegarsi al server
11:21:55 Stato: In attesa di un nuovo tentativo...
11:22:00 Stato: Risoluzione dell'indirizzo IP saturnoweb.+++++++.it in corso
11:22:00 Stato: Connessione a 168.119.++++:21...
11:22:00 Stato: Connessione stabilita, in attesa del messaggio di benvenuto...
11:22:00 Risposta: 220---------- Welcome to Pure-FTPd [privsep] [TLS] ----------
11:22:00 Risposta: 220-You are user number 47 of 50 allowed.
11:22:00 Risposta: 220-Local time is now 11:22. Server port: 21.
11:22:00 Risposta: 220-This is a private system - No anonymous login
11:22:00 Risposta: 220-IPv6 connections are also welcome on this server.
11:22:00 Risposta: 220 You will be disconnected after 15 minutes of inactivity.

Good morning I keep getting this error even though the pure ftp conf is the following:

/etc/pure-ftpd/pure-ftpd.conf
# Maximum number of simultaneous users
MaxClientsNumber 350
# Run as a background process
Daemonize yes
# Maximum number of simultaneous clients with the same IP address
MaxClientsPerIP 50

cat /etc/pure-ftpd/conf/PassivePortRange
29799 30300

the ports are born on the firewall.

it seems that my pure ftp doesn't care about my configurations and does what I want.
Help me please, it keeps kicking out users
alessio