Navicat 连不上首先需要看具体报错，

1. 如果报错如下
   Host '*' is not allowed to connect to this MariaDB server
   解决方案如下：

grant all privileges on*.* to'root' @'%' identified by 'root' with grant option;

flush privileges;  

2. 如果执行第一步还连接不上，报错如下：
   Can't connect to MySQL server on 'x.x.x.x'(10038)
   检测一下防火墙是否关闭，
   本人是centos 7.6

systemctl status firewalld              # 查看防火墙状态

如果 Active: active (running)

systemctl stop firewalld                 # 临时关闭防火墙
systemctl disable firewalld            #永久关闭,即设置开机的时候不自动启动