Matomo on Synology DS720+

Hello to all,
I am trying to install Matomo on my Synology DS720 +.
The system check passes successfully.
I’m stuck at the database settings.
I have the following error: Error connecting to database server: Connection refused
I tried to set both localhost and as Database Server and the name I gave to my nas but nothing done.
Should the my.cnf file be configured?
Thanks for the answers …