mySQL connection fails

I have two CENTOS servers A and B, and have two WP sites working properly, one in each server. Now I am trying to a site from server A to B, and get the following error when testing the database connection

Error Processing Request
An error occurred while testing the database connection! Please Try Again…
If the error persists contact your host for database connection requirements.
Status details: success

I wrote a PHP code to test the access by myself, using mysqli functions, and the access works fine, but does not work when testing with duplicator (localhost, same database, same user, same password).

I even try to check using the database and user being used by the working WP web page, without success, but the WP site does work well.

I have been reading the forum, and found an similar issue a year ago, which is marked as resolved, but with no description of the solution. I also created a duplicate of the site in B and tried to install in in B (same server) and run on the same error.
As a last test, the same package works well on a third server (wamp server).

Finally, I ran the test script from https://snapcreek.com/duplicator/docs/faqs-tech/#faq-installer-100-q and got a success message.

Any help would be great ??

Thanks in advance !!

Here is the installer log (edited)
——————————————
********************************************************************************
* DUPLICATOR-PRO: Install-Log
* STEP-1 START @ 02:57:55
* VERSION: 1.3.16
* NOTICE: Do NOT post to public sites or forums!!
********************************************************************************
PACKAGE INFO________ CURRENT SERVER |ORIGINAL SERVER
PHP VERSION_________: 5.4.16 |5.4.16
OS__________________: Linux |Linux
CREATED_____________: 2019-07-11 14:36:27
WP VERSION__________: 4.9.10
DUP VERSION_________: 1.3.16
DB__________________: 5.7.26
DB TABLES___________: 20
DB ROWS_____________: 6,232
DB FILE SIZE________: 2.34MB
********************************************************************************
SERVER INFO
PHP_________________: 5.4.16 | SAPI: apache2handler
PHP MEMORY__________: 4294967296 | SUHOSIN: disabled
SERVER______________: Apache/2.4.6 (CentOS) OpenSSL/1.0.2k-fips PHP/5.4.16
DOC ROOT____________: “….”
DOC ROOT 755________: true
LOG FILE 644________: true
REQUEST URL_________: “…./dup-installer/main.installer.php”
********************************************************************************
USER INPUTS
ARCHIVE ENGINE______: “shellexec_unzip”
SET DIR PERMS_______: 1
DIR PERMS VALUE_____: 1363
SET FILE PERMS______: 1
FILE PERMS VALUE____: 1204
SAFE MODE___________: “0”
LOGGING_____________: “1”
CONFIG MODE_________: “NEW”
FILE TIME___________: “current”
********************************************************************************

————————————–
ARCHIVE SETUP
————————————–
NAME________________: “….._archive.zip”
SIZE________________: 124.03MB

PRE-EXTRACT-CHECKS
– PASS: Apache ‘.htaccess’ not found – no backup needed.
– PASS: Microsoft IIS ‘web.config’ not found – no backup needed.
– PASS: WordFence ‘.user.ini’ not found – no backup needed.

START ZIP FILE EXTRACTION SHELLEXEC >>>
>>> Starting Shell-Exec Unzip:
Command: unzip -o -qq ‘….._archive.zip’ -d ‘…..’ 2>&1
<<< Shell-Exec Unzip Complete.
————————————–
POST-EXTACT-CHECKS
————————————–
PERMISSION UPDATES:
-DIRS: ‘755’
-FILES: ‘644’
[PHP ERR][WARN] MSG:touch(): Utime failed: Permission denied [CODE:2|FILE:……/dup-installer/ctrls/ctrl.s1.php|LINE:402]

STEP-1 COMPLETE @ 02:58:28 – RUNTIME: 32.7591 sec.

INSTALLER ERROR:
[PHP ERR][FATAL] MSG:Call to undefined function get_option() [CODE:1|FILE:…./dup-installer/lib/snaplib/class.snaplib.u.util.php|LINE:454]

INSTALLER ERROR:
[PHP ERR][FATAL] MSG:Call to undefined function get_option() [CODE:1|FILE:…../dup-installer/lib/snaplib/class.snaplib.u.util.php|LINE:454]

INSTALLER ERROR:
[PHP ERR][FATAL] MSG:Call to undefined function get_option() [CODE:1|FILE:…../dup-installer/lib/snaplib/class.snaplib.u.util.php|LINE:454]