Hi, it was a while ago but I used this post to set up the master server: https://www.howtoforge.com/tutorial...-9-stretch-apache-bind-dovecot-ispconfig-3-1/ At this point, the server wasn't meant to be a multiserver so I followed all steps and not only the first 6. Then I used this post to tweak the master server and to set up the SQL slave server: https://www.howtoforge.com/multiser...se-servers-on-debian-squeeze-with-ispconfig-3 As many of you, I'm getting this error: ERROR 1130 (HY000): Host 'ns1.ip-xx.eu' is not allowed to connect to this MariaDB server /etc/hosts on master server 127.0.0.1 localhost 127.0.1.1 ns1.ip-xx.eu ns1 192.168.0.100 ns2.ip-xx.eu 192.168.0.101 ns1.ip-xx.eu /etc/hosts on slave server 127.0.0.1 localhost 127.0.1.1 ns2.ip-xx.eu ns2 192.168.0.100 ns2.ip-xx.eu 192.168.0.101 ns1.ip-xx.eu ping is working. /etc/mysql/mariadb.conf.d/50-server.cnf on master and slave servers bind-address = 0.0.0.0 On the master server, I created root users like so, all with the same password and granted them full privileges: 'root'@'192.168.0.100' 'root'@'ns2.ip-xx.eu' 'root'@'%' My issue is at this point. The slave server cannot connect to the master sql server, so I can't set up ispconfig correctly. I'm doing: mysql -h ns1.ip-xx.eu -u root -p or mysql -h 192.168.0.101 -u root -p but getting all the time the same message. I have a firewall on the master server (I've nothing configured in the firewall of ISPConfig though) but the command netstat -anp | grep 3306 on both servers gives me something similar to: tcp 0 0 0.0.0.0:3306 0.0.0.0:* LISTEN 6649/mysqld Also, something weird, on the master server, when I do mysql -h 192.168.0.100 -u root -p or mysql -h ns2.ip-xx.eu -u root -p, it seems I'm connected to the master sql server and not the slave sql server. Indeed, SELECT User FROM mysql.user; gives me all my sql users created with ispconfig. And mysql -h 192.168.0.101 -u root -p gives me: ERROR 1130 (HY000): Host 'ns2.ip-xx.eu' is not allowed to connect to this MariaDB server I think I might have a problem with IPs. What do you think?