Web-UI not usable when a download is running

When downloading via the web interface (I tested it with a 2.4GB ISO) the interface can no longer be used and the Nextlocud server does not react anymore. Until the download is finished.

How can I fix this?

Steps to reproduce

  1. Upload a large file (2,4GB-ISO have been tested)
  2. Download it over web-ui
  3. The server will then not respond to any further actions.

Expected behaviour

Parallel work should continue to be possible. Other users e.g.

Actual behaviour

Currently only one user can download something because the server will not react anymore.

Server configuration

Operating system: Debian 9.9 (stretch)

Web server: Apache 2.4.25

Database:: MariaDB 10.2.27

PHP version: PHP-FPM 7.3

Nextcloud version: 16.0.5.1

Updated from an older Nextcloud/ownCloud or fresh install: I come from version 13, and then always updated to the next stable

Where did you install Nextcloud from: Self-hosted Nextcloud

Signing status:

Signing status
No errors have been found.

List of activated apps:

App list
Enabled:
  - activity: 2.9.1
  - bookmarks: 2.2.0
  - calendar: 1.7.1
  - checksum: 0.4.3
  - circles: 0.17.8
  - cloud_federation_api: 0.2.0
  - comments: 1.6.0
  - contacts: 3.1.6
  - dav: 1.9.2
  - deck: 0.6.6
  - external: 3.3.1
  - extract: 1.2.0
  - federatedfilesharing: 1.6.0
  - federation: 1.6.0
  - files: 1.11.0
  - files_pdfviewer: 1.5.0
  - files_rightclick: 0.15.1
  - files_sharing: 1.8.0
  - files_texteditor: 2.8.0
  - files_trashbin: 1.6.0
  - files_versions: 1.9.0
  - files_videoplayer: 1.5.0
  - gallery: 18.3.0
  - groupfolders: 4.1.3
  - logreader: 2.1.0
  - lookup_server_connector: 1.4.0
  - maps: 0.1.2
  - metadata: 0.10.0
  - news: 14.0.1
  - nextcloud_announcements: 1.5.0
  - notes: 3.0.3
  - notifications: 2.4.1
  - oauth2: 1.4.2
  - ocdownloader: 1.7.3
  - password_policy: 1.6.0
  - privacy: 1.0.0
  - provisioning_api: 1.6.0
  - serverinfo: 1.6.0
  - sharebymail: 1.6.0
  - survey_client: 1.4.0
  - systemtags: 1.6.0
  - tasks: 0.11.3
  - text: 1.0.2
  - theming: 1.7.0
  - twofactor_backupcodes: 1.5.0
  - twofactor_totp: 3.0.1
  - updatenotification: 1.6.0
  - viewer: 1.1.0
  - workflowengine: 1.6.0
Disabled:
  - accessibility
  - admin_audit
  - audioplayer
  - audioplayer_editor
  - encryption
  - files_automatedtagging
  - files_external
  - files_markdown
  - files_mindmap
  - firstrunwizard
  - polls
  - quota_warning
  - recommendations
  - support
  - user_ldap

Nextcloud configuration:

Config report
{
    "system": {
        "instanceid": "***REMOVED SENSITIVE VALUE***",
        "passwordsalt": "***REMOVED SENSITIVE VALUE***",
        "secret": "***REMOVED SENSITIVE VALUE***",
        "trusted_domains": [
            ""***REMOVED SENSITIVE VALUE***",
        ],
        "datadirectory": "***REMOVED SENSITIVE VALUE***",
        "dbtype": "mysql",
        "version": "16.0.5.1",
        "overwrite.cli.url": "https:\/\/share.mi-luriel.org",
        "htaccess.RewriteBase": "\/",
        "dbname": "***REMOVED SENSITIVE VALUE***",
        "dbhost": "***REMOVED SENSITIVE VALUE***",
        "dbport": "",
        "dbtableprefix": "oc_",
        "mysql.utf8mb4": true,
        "dbuser": "***REMOVED SENSITIVE VALUE***",
        "dbpassword": "***REMOVED SENSITIVE VALUE***",
        "installed": true,
        "trashbin_retention_obligation": "D1, D2",
        "memcache.local": "\\OC\\Memcache\\APCu",
        "mail_smtpmode": "smtp",
        "mail_smtpsecure": "ssl",
        "mail_sendmailmode": "smtp",
        "mail_from_address": "***REMOVED SENSITIVE VALUE***",
        "mail_domain": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpauthtype": "PLAIN",
        "mail_smtpauth": 1,
        "mail_smtphost": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpport": "465",
        "mail_smtpname": "***REMOVED SENSITIVE VALUE***",
        "mail_smtppassword": "***REMOVED SENSITIVE VALUE***",
        "maintenance": false,
        "twofactor_enforced": "true",
        "twofactor_enforced_groups": [
            "admin"
        ],
        "twofactor_enforced_excluded_groups": [],
        "has_rebuilt_cache": true
    }
}

Are you using external storage, if yes which one: no

Are you using encryption: no

Are you using an external user-backend, if yes which one: no

Client configuration

Browser: Firefox 69.0.3

Operating system: Manjaro-Linux-Stable

Logs

Web server error log

Web server error log
No errors there

Nextcloud log (data/nextcloud.log)

Nextcloud log
No errors there

I found the mistake.

php-fpm child-processes were set too small.

Sorry to bother you.