cURL error 28: Connection timed out with latest Docker image

I’m getting the following error message when I try to open a document with Collabora:

[richdocuments] Error: GuzzleHttp\Exception\ConnectException: cURL error 28: Connection timed out after 5001 milliseconds (see http://curl.haxx.se/libcurl/c/libcurl-errors.html) at <<closure>>

 0. /var/www/html/3rdparty/guzzlehttp/guzzle/src/Handler/CurlFactory.php line 149
    GuzzleHttp\Handler\CurlFactory::createRejection(GuzzleHttp\Handl ... l}, {errno: 28,error ... "})
 1. /var/www/html/3rdparty/guzzlehttp/guzzle/src/Handler/CurlFactory.php line 102
    GuzzleHttp\Handler\CurlFactory::finishError(GuzzleHttp\Handler\CurlHandler {}, GuzzleHttp\Handl ... l}, GuzzleHttp\Handler\CurlFactory {})
 2. /var/www/html/3rdparty/guzzlehttp/guzzle/src/Handler/CurlHandler.php line 43
    GuzzleHttp\Handler\CurlFactory::finish(GuzzleHttp\Handler\CurlHandler {}, GuzzleHttp\Handl ... l}, GuzzleHttp\Handler\CurlFactory {})
 3. /var/www/html/3rdparty/guzzlehttp/guzzle/src/Handler/Proxy.php line 28
    GuzzleHttp\Handler\CurlHandler->__invoke("*** sensitive parameter replaced ***", "*** sensitive parameter replaced ***")
 4. /var/www/html/3rdparty/guzzlehttp/guzzle/src/Handler/Proxy.php line 51
    GuzzleHttp\Handler\Proxy::GuzzleHttp\Handler\{closure}("*** sensitive parameters replaced ***")
 5. /var/www/html/3rdparty/guzzlehttp/guzzle/src/PrepareBodyMiddleware.php line 37
    GuzzleHttp\Handler\Proxy::GuzzleHttp\Handler\{closure}("*** sensitive parameters replaced ***")
 6. /var/www/html/3rdparty/guzzlehttp/guzzle/src/Middleware.php line 30
    GuzzleHttp\PrepareBodyMiddleware->__invoke("*** sensitive parameter replaced ***", "*** sensitive parameter replaced ***")
 7. /var/www/html/3rdparty/guzzlehttp/guzzle/src/RedirectMiddleware.php line 70
    GuzzleHttp\Middleware::GuzzleHttp\{closure}("*** sensitive parameters replaced ***")
 8. /var/www/html/3rdparty/guzzlehttp/guzzle/src/Middleware.php line 60
    GuzzleHttp\RedirectMiddleware->__invoke("*** sensitive parameter replaced ***", "*** sensitive parameter replaced ***")
 9. /var/www/html/3rdparty/guzzlehttp/guzzle/src/HandlerStack.php line 67
    GuzzleHttp\Middleware::GuzzleHttp\{closure}("*** sensitive parameters replaced ***")
10. /var/www/html/3rdparty/guzzlehttp/guzzle/src/Client.php line 277
    GuzzleHttp\HandlerStack->__invoke("*** sensitive parameter replaced ***", "*** sensitive parameter replaced ***")
11. /var/www/html/3rdparty/guzzlehttp/guzzle/src/Client.php line 125
    GuzzleHttp\Client->transfer("*** sensitive parameter replaced ***", "*** sensitive parameter replaced ***")
12. /var/www/html/3rdparty/guzzlehttp/guzzle/src/Client.php line 131
    GuzzleHttp\Client->requestAsync("get", GuzzleHttp\Psr7\Uri {}, {verify: "/var/w ... }})
13. /var/www/html/lib/private/Http/Client/Client.php line 161
    GuzzleHttp\Client->request("get", "https://office. ... y", {verify: "/var/w ... e})
14. /var/www/html/apps/richdocuments/lib/WOPI/DiscoveryManager.php line 106
    OC\Http\Client\Client->get("https://office. ... y", {timeout: 5})
15. /var/www/html/apps/richdocuments/lib/WOPI/DiscoveryManager.php line 78
    OCA\Richdocuments\WOPI\DiscoveryManager->fetchFromRemote()
16. /var/www/html/apps/richdocuments/lib/WOPI/Parser.php line 41
    OCA\Richdocuments\WOPI\DiscoveryManager->get()
17. /var/www/html/apps/richdocuments/lib/TokenManager.php line 166
    OCA\Richdocuments\WOPI\Parser->getUrlSrc("application/vnd ... t")
18. /var/www/html/apps/richdocuments/lib/Controller/DocumentController.php line 176
    OCA\Richdocuments\TokenManager->getToken("*** sensitive parameters replaced ***")
19. /var/www/html/lib/private/AppFramework/Http/Dispatcher.php line 166
    OCA\Richdocuments\Controller\DocumentController->index("*** sensitive parameter replaced ***")
20. /var/www/html/lib/private/AppFramework/Http/Dispatcher.php line 99
    OC\AppFramework\Http\Dispatcher->executeController(OCA\Richdocument ... {}, "index")
21. /var/www/html/lib/private/AppFramework/App.php line 126
    OC\AppFramework\Http\Dispatcher->dispatch(OCA\Richdocument ... {}, "index")
22. /var/www/html/lib/private/AppFramework/Routing/RouteActionHandler.php line 47
    OC\AppFramework\App::main("OCA\\Richdocume ... r", "index", OC\AppFramework\ ... {}, {_route: "richdocuments.document.index"})
23. <<closure>>
    OC\AppFramework\Routing\RouteActionHandler->__invoke({_route: "richdocuments.document.index"})
24. /var/www/html/lib/private/Route/Router.php line 297
    undefinedundefinedcall_user_func(OC\AppFramework\ ... {}, {_route: "richdocuments.document.index"})
25. /var/www/html/lib/base.php line 975
    OC\Route\Router->match("/apps/richdocuments/index")
26. /var/www/html/index.php line 42
    OC::handleRequest()

GET /index.php/apps/richdocuments/index?fileId=72478&requesttoken=%2BYbBRXDPQj9%2FGyM5Pa9s6JNovXbTvC0%2BQXrcLwQyHwc%3D%3AkteufCOWBXpKTk5bZ%2FYkscAAiQyD62RqdA2%2BH0BbRSg%3D
from 62.119.168.113 by user at 2019-05-16T12:18:40+00:00

I’m using docker with Traefik as a proxy. It worked just a week ago before I updated the linux kernel.

Useful info:

Distributor ID: Debian
Description: Debian GNU/Linux 9.9 (stretch)
Release: 9.9
Codename: stretch
Linux kernel: 4.9.0-9-amd64

Docker:

Client:
Version: 18.09.6
API version: 1.39
Go version: go1.10.8
Git commit: 481bc77
Built: Sat May 4 02:36:00 2019
OS/Arch: linux/amd64
Experimental: false

Server: Docker Engine - Community
Engine:
Version: 18.09.6
API version: 1.39 (minimum version 1.12)
Go version: go1.10.8
Git commit: 481bc77
Built: Sat May 4 01:59:36 2019
OS/Arch: linux/amd64
Experimental: false

Docker-compose:

version: '3'

services:

  db:
    image: postgres
    container_name: nextcloud_db
    restart: always
    volumes:
      - db:/var/lib/postgresql/data
      - /etc/localtime:/etc/localtime:ro
    env_file:
      - db.env
    networks:
      - internal
    labels:
      - "traefik.enable=false"

  app:
    image: nextcloud:latest
    container_name: nextcloud_app
    hostname: nextcloud
    restart: always
    volumes:
      - nextcloud:/var/www/html
      - ./nextcloud/config:/var/www/html/config
      - ./nextcloud/custom_apps:/var/www/html/custom_apps
      - ./nextcloud/data:/var/www/html/data
      - ./nextcloud/themes:/var/www/html/themes
      - /etc/localtime:/etc/localtime:ro
      - /mnt/vol1/nextcloud:/mnt/vol1
    env_file:
      - db.env
    depends_on:
      - db
    networks:
      - web
      - internal
    labels:
      - "traefik.backend=nextcloud"
      - "traefik.docker.network=web"
      - "traefik.enable=true"
      - "traefik.frontend.rule=Host: cloud.domain.com"
      - "traefik.port=80"
      - "traefik.frontend.headers.STSSeconds=15552000"
      - "traefik.frontend.headers.referrerPolicy=no-referrer"
      - "traefik.frontend.redirect.permanent=true"
      - "traefik.frontend.redirect.regex=https://(.*)/.well-known/(card|cal)dav"
      - "traefik.frontend.redirect.replacement=https://$$1/remote.php/dav/"

  collabora:
    image: collabora/code:latest
    container_name: nextcloud_collabora
    hostname: collabora
    restart: always
    environment:
      - "extra_params=--o:ssl.enable=false --o:ssl.termination=true"
      - "domain=cloud\\.domain\\.com"
      - "SLEEPFORDEBUGGER=0"
      - "username=user"
      - "password=omitted"
    labels:
      - "traefik.frontend.rule=Host:office.domain.com"
      - "traefik.port=9980"
      - "traefik.docker.network=web"
      - "traefik.enable=true"
    cap_add:
      - MKNOD
    volumes:
      - /etc/localtime:/etc/localtime:ro
    networks:
      - web
      - internal
    
  redis:
    image: redis
    container_name: nextcloud_redis
    restart: always
    volumes:
      - /docker/nextcloud/redis:/data
      - /etc/localtime:/etc/localtime:ro
    networks:
      - internal
    sysctls:
      net.core.somaxconn: '511'
    labels:
      - "traefik.enable=false"

networks:
  internal:
    web:
      external: true
    
volumes:
  db:
  nextcloud:
  document_data:
  document_log:

Thank you in advance.