Grafana on Debian 11 system: curl http://localhost:3000 --> connection refused

Question

I have a really hard time with my Grafana on a Debian 11 system. The server seems to be running fine in principle, but I cannot reach it. This happened after I did apt-get upgrade and update on the system.

I already went with Google Gemini through all kind of ideas but without success.

This is my latest state:

[server]
protocol = http
http_addr = 0.0.0.0
http_port = 3000
domain = localhost
root_url = %(protocol)s://%(domain)s:%(http_port)s/
serve_from_sub_path = false
enable_gzip = true
*********************************************************
The output of "sudo journalctl -u grafana-server" produces the following errors (I omitted info messages). I believe these are unrelated to our problem:
May 13 17:03:32 lxyrpc01 grafana-server[3266411]: logger=renderer.manager t=2025年05月13日T17:03:32.174833164+02:00 level=error msg="Failed to get renderer plugin sources" error="failed to open plugins path"
May 13 17:03:32 lxyrpc01 grafana-server[3266411]: logger=plugin.sources t=2025年05月13日T17:03:32.196824299+02:00 level=error msg="Failed to load external plugins" error="failed to open plugins path"
May 13 17:03:32 lxyrpc01 grafana-server[3266411]: logger=plugins.registration t=2025年05月13日T17:03:32.222162484+02:00 level=error msg="Could not register plugin" pluginId=table error="plugin table is already registered"
May 13 17:03:32 lxyrpc01 grafana-server[3266411]: logger=plugins.initialization t=2025年05月13日T17:03:32.22231334+02:00 level=error msg="Could not initialize plugin" pluginId=table error="plugin table is already registered"
May 13 17:03:32 lxyrpc01 grafana-server[3266411]: logger=renderer.manager t=2025年05月13日T17:03:32.262007163+02:00 level=error msg="Failed to get renderer plugin sources" error="failed to open plugins path"
May 13 17:03:42 lxyrpc01 grafana-server[3266411]: logger=plugin.signature.key_retriever t=2025年05月13日T17:03:42.246810873+02:00 level=error msg="Error downloading plugin manifest keys" error="Get \"https://grafana.com/api/plugins/ci/keys\": context deadline exceeded (Client.Timeout exceeded while awaiting headers)"
May 13 17:03:42 lxyrpc01 grafana-server[3266411]: logger=plugin.backgroundinstaller t=2025年05月13日T17:03:42.24922406+02:00 level=error msg="Failed to install plugin" pluginId=grafana-lokiexplore-app version= error="Get \"https://grafana.com/api/plugins/grafana-lokiexplore-app/versions\": context deadline exceeded (Client.Timeout exceeded while awaiting headers)"
May 13 17:03:42 lxyrpc01 grafana-server[3266411]: logger=grafana.update.checker t=2025年05月13日T17:03:42.262801631+02:00 level=error msg="Update check failed" error="failed to get stable version from grafana.com: Get \"https://grafana.com/api/grafana/versions/stable\": dial tcp 34.120.177.193:443: i/o timeout" duration=10.000563189s
May 13 17:03:42 lxyrpc01 grafana-server[3266411]: logger=plugin.angulardetectorsprovider.dynamic t=2025年05月13日T17:03:42.40725765+02:00 level=error msg="Error while updating detectors" error="fetch: http do: Get \"https://grafana.com/api/plugins/angular_patterns\": context deadline exceeded (Client.Timeout exceeded while awaiting headers)"
May 13 17:03:52 lxyrpc01 grafana-server[3266411]: logger=plugin.backgroundinstaller t=2025年05月13日T17:03:52.250220389+02:00 level=error msg="Failed to install plugin" pluginId=grafana-pyroscope-app version= error="Get \"https://grafana.com/api/plugins/grafana-pyroscope-app/versions\": context deadline exceeded (Client.Timeout exceeded while awaiting headers)"
May 13 17:04:02 lxyrpc01 grafana-server[3266411]: logger=plugin.backgroundinstaller t=2025年05月13日T17:04:02.250455623+02:00 level=error msg="Failed to install plugin" pluginId=grafana-exploretraces-app version= error="Get \"https://grafana.com/api/plugins/grafana-exploretraces-app/versions\": context deadline exceeded (Client.Timeout exceeded while awaiting headers)"
May 13 17:04:12 lxyrpc01 grafana-server[3266411]: logger=plugin.backgroundinstaller t=2025年05月13日T17:04:12.251363296+02:00 level=error msg="Failed to install plugin" pluginId=grafana-metricsdrilldown-app version= error="Get \"https://grafana.com/api/plugins/grafana-metricsdrilldown-app/versions\": context deadline exceeded (Client.Timeout exceeded while awaiting headers)"
May 13 17:04:52 lxyrpc01 grafana-server[3266411]: logger=plugin.signature.key_retriever t=2025年05月13日T17:04:52.250370429+02:00 level=error msg="Error downloading plugin manifest keys" error="Get \"https://grafana.com/api/plugins/ci/keys\": context deadline exceeded (Client.Timeout exceeded while awaiting headers)"
*********************************************************
"sudo systemctl status grafana-server" yields:
●くろまる grafana-server.service - Grafana instance
 Loaded: loaded (/lib/systemd/system/grafana-server.service; enabled; vendor preset: enabled)
 Active: active (running) since Tue 2025年05月13日 17:03:31 CEST; 9min ago
 Docs: http://docs.grafana.org
 Main PID: 3266410 (bash)
 Tasks: 22 (limit: 38470)
 Memory: 102.3M
 CPU: 3.841s
 CGroup: /system.slice/grafana-server.service
 ├─3266410 bash /usr/sbin/grafana-server --config=/srv/grafana/config/grafana.ini --pidfile=/run/grafana/grafana-server.pid --packaging=deb cfg:default.paths.logs=/srv/grafana/log cfg:default.paths.data=/srv/grafana/data cfg:default>
 └─3266411 /usr/share/grafana/bin/grafana server --config=/srv/grafana/config/grafana.ini --pidfile=/run/grafana/grafana-server.pid --packaging=deb cfg:default.paths.logs=/srv/grafana/log cfg:default.paths.data=/srv/grafana/data cfg>
May 13 17:03:42 lxyrpc01 grafana-server[3266411]: logger=grafana.update.checker t=2025年05月13日T17:03:42.262801631+02:00 level=error msg="Update check failed" error="failed to get stable version from grafana.com: Get \"https://grafana.com/api/graf>
May 13 17:03:42 lxyrpc01 grafana-server[3266411]: logger=plugin.angulardetectorsprovider.dynamic t=2025年05月13日T17:03:42.40725765+02:00 level=error msg="Error while updating detectors" error="fetch: http do: Get \"https://grafana.com/api/plugins/>
May 13 17:03:42 lxyrpc01 grafana-server[3266411]: logger=plugin.angulardetectorsprovider.dynamic t=2025年05月13日T17:03:42.407321372+02:00 level=info msg="Patterns update finished" duration=10.001050487s
May 13 17:03:52 lxyrpc01 grafana-server[3266411]: logger=plugin.backgroundinstaller t=2025年05月13日T17:03:52.250220389+02:00 level=error msg="Failed to install plugin" pluginId=grafana-pyroscope-app version= error="Get \"https://grafana.com/api/pl>
May 13 17:03:52 lxyrpc01 grafana-server[3266411]: logger=plugin.backgroundinstaller t=2025年05月13日T17:03:52.250326183+02:00 level=info msg="Installing plugin" pluginId=grafana-exploretraces-app version=
May 13 17:04:02 lxyrpc01 grafana-server[3266411]: logger=plugin.backgroundinstaller t=2025年05月13日T17:04:02.250455623+02:00 level=error msg="Failed to install plugin" pluginId=grafana-exploretraces-app version= error="Get \"https://grafana.com/ap>
May 13 17:04:02 lxyrpc01 grafana-server[3266411]: logger=plugin.backgroundinstaller t=2025年05月13日T17:04:02.250601689+02:00 level=info msg="Installing plugin" pluginId=grafana-metricsdrilldown-app version=
May 13 17:04:12 lxyrpc01 grafana-server[3266411]: logger=plugin.backgroundinstaller t=2025年05月13日T17:04:12.251363296+02:00 level=error msg="Failed to install plugin" pluginId=grafana-metricsdrilldown-app version= error="Get \"https://grafana.com>
May 13 17:04:52 lxyrpc01 grafana-server[3266411]: logger=plugin.signature.key_retriever t=2025年05月13日T17:04:52.250370429+02:00 level=error msg="Error downloading plugin manifest keys" error="Get \"https://grafana.com/api/plugins/ci/keys\": conte>
May 13 17:05:00 lxyrpc01 grafana-server[3266411]: logger=infra.usagestats t=2025年05月13日T17:05:00.252315077+02:00 level=info msg="Usage stats are ready to report"
*********************************************************
"curl http://localhost:3000" still show "refused" error message
*********************************************************
result of "sudo ss -tulnp | grep ':3000'":" --> tcp LISTEN 0 4096 *:3000 *:* users:(("grafana",pid=3266411,fd=18)) 
*********************************************************
Output of "telnet -4 localhost 3000":
Trying 127.0.0.1...
Trying 127.0.0.1...
telnet: Unable to connect to remote host: Connection refused

I tried as well to explicitly binding grafana to localhost to avoid issues with ip6 (our network is not configured for ip6):

[server]
http_addr = 127.0.0.1

Yielding netstat -lt:

tcp 0 0 localhost:3000 0.0.0.0:* LISTEN 

still "connection refused"...

• AlexD: Incorrectly configured firewall?
• WolfiG: Nope, I checked the firewall and is ok.