Connection timeout mysql php problem when server is fully available?

Question

PHP

Hello.
There are 4 servers 2 with php + nginx and 2 with mysql 8 (main base and replication).
Recently, an error began to appear when trying to connect php to mysql , mysql connection timeout while mysql is always available (both the main database and replication).
There is no packet loss between servers.
Mysql databases are not loaded.
When a problem occurs, I can safely connect through mysqlworkbench and everything is fine there.
Before that, there were problems with one of the routers in the data center, but the DC representative says that everything is ok and the problem is not on their side.
And such a problem appears simultaneously when connecting from 2 separate servers to 2 others)
1. Php nginx to 1. Mysql8 (main database)
2. Php nginx on 2 . Mysql 8 (replication)
Both pairs of servers have errors at the same time.
PDOException error: SQLSTATE[HY000] [2002] Connection timeout
Has anyone encountered this problem?

Answer 1

Specify error and number.
https://confluence.atlassian.com/stashkb/connectio...
so try