[Warning] [MY-010068] [Server] CA certificate /var/lib/mysql/ca.pem is self sign

problema con wordpress y mysql. Si necesitan algun log os lo muestro, una ayuda por favor

/var/log/mysql/error.log

Código

2018-11-26T23:04:12.003546Z 0 [System] [MY-010910] [Server] /usr/sbin/mysqld: Shutdown complete (mysqld 8.0.13)  MySQL Community Server - GPL.
2018-11-26T23:04:12.693353Z 0 [System] [MY-010116] [Server] /usr/sbin/mysqld (mysqld 8.0.13) starting as process 1944
2018-11-26T23:04:14.513703Z 0 [Warning] [MY-010068] [Server] CA certificate /var/lib/mysql/ca.pem is self signed.
2018-11-26T23:04:14.574313Z 0 [System] [MY-010931] [Server] /usr/sbin/mysqld: ready for connections. Version: '8.0.13'  socket: '/var/run/mysqld/mysqld.sock'  port: 3306  MySQL Community Server - GPL.
2018-11-26T23:04:14.756353Z 0 [System] [MY-011323] [Server] X Plugin ready for connections. Socket: '/var/run/mysqld/mysqlx.sock' bind-address: '::' port: 33060
2018-11-26T23:16:30.055092Z 0 [System] [MY-010910] [Server] /usr/sbin/mysqld: Shutdown complete (mysqld 8.0.13)  MySQL Community Server - GPL.
2018-11-26T23:16:30.782675Z 0 [System] [MY-010116] [Server] /usr/sbin/mysqld (mysqld 8.0.13) starting as process 2175
2018-11-26T23:16:32.833066Z 0 [Warning] [MY-010068] [Server] CA certificate /var/lib/mysql/ca.pem is self signed.
2018-11-26T23:16:32.908563Z 0 [System] [MY-010931] [Server] /usr/sbin/mysqld: ready for connections. Version: '8.0.13'  socket: '/var/run/mysqld/mysqld.sock'  port: 3306  MySQL Community Server - GPL.
2018-11-26T23:16:32.921263Z 0 [System] [MY-011323] [Server] X Plugin ready for connections. Socket: '/var/run/mysqld/mysqlx.sock' bind-address: '::' port: 33060

Wordpress al instalar me muestra esto por navegador 192.168.1.11/wp-admin/install.php

The server requested authentication method unknown to the client

Error establishing a database connection
This either means that the username and password information in your wp-config.php file is incorrect or we can’t contact the database server at localhost. This could mean your host’s database server is down.

Are you sure you have the correct username and password?
Are you sure that you have typed the correct hostname?
Are you sure that the database server is running?
If you’re unsure what these terms mean you should probably contact your host. If you still need help you can always visit the WordPress Support Forums.