tp5.1 Why does it sometimes show that the database cannot be found when connecting to mysql in the php toolbox, but sometimes the connection is successful?

Question

tp5.1 Why does it sometimes show that the database cannot be found when connecting to mysql in the php toolbox, and sometimes it can connect successfully. The error display is the page that often appears. When it succeeds, it can connect to the database successfully, and the data inside can all be read. I wrote the code yesterday, but it showed that it could not connect to the database. It was also the same at the beginning today. The code was not changed, and suddenly it was working. After a while, it was not working again, and now it is successfully connected again. What is the reason? Is mysql in the php toolbox not working? has a problem? Does any master know?