Symfony 4.2.8 : Can't connect to ES 7.10 through the fos:elastica:populate command

Question

I encounter a problem in my production site in Symfony 4.2.8 (yes I know...).

When I try to launch a bin/console fos:elastica:populate or bin/console fos:elastica:reset the console crash (with -vvv option) :

Exception trace:
 () at /var/www/current/vendor/ruflin/elastica/lib/Elastica/Transport/Http.php:190
 Elastica\Transport\Http->exec() at /var/www/current/vendor/ruflin/elastica/lib/Elastica/Request.php:194
 Elastica\Request->send() at /var/www/current/vendor/ruflin/elastica/lib/Elastica/Client.php:689
 Elastica\Client->request() at /var/www/current/vendor/friendsofsymfony/elastica-bundle/src/Elastica/Client.php:58
 FOS\ElasticaBundle\Elastica\Client->request() at /var/www/current/vendor/ruflin/elastica/lib/Elastica/Client.php:721
 Elastica\Client->requestEndpoint() at /var/www/current/vendor/ruflin/elastica/lib/Elastica/Index.php:586
 Elastica\Index->requestEndpoint() at /var/www/current/vendor/ruflin/elastica/lib/Elastica/Index.php:225
 Elastica\Index->delete() at /var/www/current/vendor/ruflin/elastica/lib/Elastica/Index.php:296
 Elastica\Index->create() at /var/www/current/vendor/friendsofsymfony/elastica-bundle/src/Index/Resetter.php:110
 FOS\ElasticaBundle\Index\Resetter->resetIndex() at /var/www/current/vendor/friendsofsymfony/elastica-bundle/src/Command/PopulateCommand.php:184
 FOS\ElasticaBundle\Command\PopulateCommand->populateIndex() at /var/www/current/vendor/friendsofsymfony/elastica-bundle/src/Command/PopulateCommand.php:164
 FOS\ElasticaBundle\Command\PopulateCommand->execute() at /var/www/current/vendor/symfony/console/Command/Command.php:255
 Symfony\Component\Console\Command\Command->run() at /var/www/current/vendor/symfony/console/Application.php:926
 Symfony\Component\Console\Application->doRunCommand() at /var/www/current/vendor/symfony/framework-bundle/Console/Application.php:89
 Symfony\Bundle\FrameworkBundle\Console\Application->doRunCommand() at /var/www/current/vendor/symfony/console/Application.php:269
 Symfony\Component\Console\Application->doRun() at /var/www/current/vendor/symfony/framework-bundle/Console/Application.php:75
 Symfony\Bundle\FrameworkBundle\Console\Application->doRun() at /var/www/current/vendor/symfony/console/Application.php:145
 Symfony\Component\Console\Application->run() at /var/www/current/bin/console:39

In Http.php line 190:

 [Elastica\Exception\Connection\HttpException]  
 Couldn't connect to host, Elasticsearch down?

A curl on ES server respond :

{
 "name" : "prod",
 "cluster_name" : "elasticsearch",
 "cluster_uuid" : "********",
 "version" : {
  "number" : "7.10.0",
  "build_flavor" : "default",
  "build_type" : "deb",
  "build_hash" : "51e9d6f22758d0374a0f3f5c6e8f3a7997850f96",
  "build_date" : "2020-11-09T21:30:33.964949Z",
  "build_snapshot" : false,
  "lucene_version" : "8.7.0",
  "minimum_wire_compatibility_version" : "6.8.0",
  "minimum_index_compatibility_version" : "6.0.0-beta1"
 },
 "tagline" : "You Know, for Search"
}

I create a new branch to upgrade all the component but I need a clue to operate a quick fix on production... If somebody have an idea thank in advance.