Connect TimeOut on MariaDB

On a VPS server I have Ubuntu 20.04 / Nginx / MariaDB
The software I want to Install: nopCommerce 4.50.1
After installing all requirements, you enter the domainname in a browser, you get a form to fill with admin credentials and the connection details for the database in separate fields or a complete connection string.
When I fill the fields I get a Nginx 502 TimeOut error after about 1 minute. 122 tables were created and an appSettings.json file with some data including the connection string.
After some attempts there was no data in the appSettings file and other times there was data, but not everything.
Can I create a connection string that extends the connection time?

Server=localhost;Database=mydatabase;Uid=user;Pwd=mypassword;