I have the following error while trying to connect SQL Server:

[Microsoft][ODBC Driver 18 for SQL Server]SSL Provider: [error:1416F086:SSL routines:tls_process_server_certificate:certificate verify failed:self signed certificate]

I'm on Ubuntu 20, PHP 7.4 FPM, nginx.

Server  Microsoft SQL Server [11.00.3128
Microsoft SQL Server 2012 (SP1) - 11.0.3128.0 (X64) 
    Dec 28 2012 20:23:12 
    Copyright (c) Microsoft Corporation
    Standard Edition (64-bit) on Windows NT 6.2  (Build 9200: ) (Hypervisor)
]

When I:

openssl s_client -connect myserverip:1433 -tls1

I get:

CONNECTED(00000003)

My openssl library version is:

OpenSSL 1.1.1f 31 Mar 2020 (Library: OpenSSL 1.1.1k 25 Mar 2021)

I have tried many things, like forcing system to use TLS1 in /etc/ssl/openssl.cnf or nginx configuration to downgrade to tls1.