ERROR: Cannot add instance ':3306' to the cluster because it has the same server ID of a member of the cluster.
Please change the server ID of the instance to add: all members must have a unique server ID.
Cluster.addInstance: The server_id '1' is already used by instance 'LAPTOP-QM0IF54I:3306'. (RuntimeError)。
[root@localhost ~]# find / -name my.cnf /etc/my.cnf [root@localhost ~]# vim /etc/my.cnf
Every server/node must have a different server_id so just open my.cnf and change /add under [mysqld] the following variable。
Save and restart Mysql after change：
[root@localhost ~]# systemctl restart mysqld