In some situations, Deskpro itself may make HTTP requests: Downloading updates, executing a webhook, consuming web APIs such as with the JIRA app, etc.
Starting with Deskpro v5.2.0, you can make Deskpro use a proxy server for these HTTP requests by editing config/advanced/config.settings.php and adding one of these three configuration variants:
$CONFIG['settings']['http_client.proxy'] = 'http://example:password@localhost:36879';
// optionally specity a list of hosts to NOT proxy
//$CONFIG['settings']['http_client.no_proxy'] = ['example.com'];