[Bug]: Federated share download starts with long delay (high TTFB) for large files (>200MB), but transfers fast once started

[parsmmm]

⚠️ This issue respects the following points: ⚠️

• This is a bug, not a question or a configuration/webserver/proxy issue.
• This issue is not already reported on Github OR Nextcloud Community Forum (I've searched it).
• Nextcloud Server is up to date. See Maintenance and Release Schedule for supported versions.
• I agree to follow Nextcloud's Code of Conduct.

Bug description

When downloading a federated share (federation) file, the download start is delayed significantly for large files (e.g., >200MB).

The problem is not the download speed: once the download starts, it downloads fast at normal speed.
The issue is the delay before the first byte is received (high TTFB / time-to-first-byte) — e.g., ~60 seconds before the download actually begins in the Nextcloud desktop client / browser.

This behavior seems to happen only for federated downloads. Normal local downloads from the same instance do not show this start delay.

Steps to reproduce

Have two Nextcloud instances connected via Federation / federated shares.

Share a large file (example: ~300MB .rar) from remote instance to local instance using federation.

From the receiving side (or via desktop client/web), start downloading the federated file.

Observe that the download does not start immediately (long waiting period), then suddenly starts and downloads quickly.

Expected behavior

Download should start immediately (normal TTFB), similar to local downloads.

Actual behavior
Download starts late (TTFB very high; e.g. ~1 minute delay for a ~300MB file), but once started it downloads fast.

Nextcloud Server version

32

Operating system

Debian/Ubuntu

PHP engine version

PHP 8.3

Web server

Nginx

Database engine version

PostgreSQL

Is this bug present after an update or on a fresh install?

Fresh Nextcloud Server install

Are you using the Nextcloud Server Encryption module?

Encryption is Disabled

What user-backends are you using?

• Default user-backend (database)
• LDAP/ Active Directory
• SSO - SAML
• Other

Configuration report

Key relevant settings verified:

davstorage.request_timeout = 3600 on both sides.

Reverse proxy config (NPM custom config) includes:

client_max_body_size 8G;

proxy_connect_timeout 3600;

proxy_read_timeout 86400s;

proxy_send_timeout 86400s;

send_timeout 86400s;

proxy_buffering off;

proxy_request_buffering off;

proxy_max_temp_file_size 0;

add_header X-Accel-Buffering no;

List of activated Apps

- group_everyone: 0.1.18
  - groupfolders: 19.1.12
  - impersonate: 2.0.0
  - logreader: 4.0.0
  - lookup_server_connector: 1.19.0
  - mail: 5.5.1
  - nextcloud-aio: 0.8.0
  - notifications: 4.0.0
  - notify_push: 1.2.1
  - oauth2: 1.19.1
  - password_policy: 3.0.0
  - passwords: 2025.9.20
  - privacy: 3.0.0
  - profile: 1.0.0
  - provisioning_api: 1.21.0
  - recommendations: 4.0.0
  - related_resources: 2.0.0
  - richdocuments: 8.7.7
  - serverinfo: 3.0.0
  - settings: 1.14.0
  - spreed: 21.1.5
  - support: 3.0.0
  - survey_client: 3.0.0
  - suspicious_login: 9.0.1
  - systemtags: 1.21.1
  - text: 5.0.0
  - theming: 2.6.1
  - twofactor_backupcodes: 1.20.0
  - twofactor_totp: 13.0.0-dev.0
  - updatenotification: 1.21.0
  - user_ldap: 1.22.0
  - user_saml: 7.0.0
  - user_status: 1.11.0
  - viewer: 4.0.0
  - weather_status: 1.11.0
  - webhook_listeners: 1.2.0
  - whiteboard: 1.4.2
  - workflowengine: 2.13.0
Disabled:
  - activity: 4.0.0 (installed 4.0.0)
  - announcementcenter: 7.2.1 (installed 7.2.1)
  - app_api: 5.0.2 (installed 4.0.6)
  - calendar: 5.5.4 (installed 5.5.4)
  - cfg_share_links: 7.0.1 (installed 7.0.1)
  - encryption: 2.19.0
  - files_antivirus: 6.0.7 (installed 6.0.7)
  - files_downloadactivity: 1.18.1 (installed 1.18.1)
  - files_trackdownloads: 1.11.0 (installed 1.11.0)
  - nextcloud_announcements: 3.0.0 (installed 1.16.0)
  - notes: 4.12.3 (installed 4.12.3)
  - photos: 4.0.0 (installed 2.5.0)
  - sharebymail: 1.21.0 (installed 1.17.0)
  - tasks: 0.16.1 (installed 0.16.1)
  - twofactor_nextcloud_notification: 5.0.0
  - user_migration: 8.0.0 (installed 8.0.0)
  - user_usage_report: 2.0.0 (installed 2.0.0)

Nextcloud Signing status

Nextcloud Logs

Additional info

Additional info

Client IP used in tests: 172.16.0.20
Quick curl timing tests to remote DAV (direct, authenticated) show low TTFB (e.g. ~0.22–0.35s using Range 0-0), so the latency seems specific to federated share download flow, not raw WebDAV serving.