Running docker preview mattermost and start call does not connect

hello, I’m running docker preview mattermost image and trying to make calls but start call failed to connect call. Appreciate any help on troubleshoot (logs or configuration) to look check to get calls to work. Please note message and text are working.

In the System Console, is the Calls plugin enabled and running? What does mattermost.log say?

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Yes, call plugins are enabled and running. mattermost log shows some error:
“timestamp”:“2025-04-10 02:00:15.526 Z”,“level”:“info”,“msg”:“Failed to fetch marketplace plugins for telemetry. Using predefined list.”,“caller”:“telemetry/telemetry.go:1524”,“error”:“Get "https://api.integrations.mattermost.com/api/v1/plugins?build_enterprise_ready=false&cloud=false&enterprise_plugins=false&filter=&local_only=false&page=0&platform=&plugin_id=&remote_only=false&return_all_versions=false&server_version=10.6.1\”: tls: failed to verify certificate: x509: certificate signed by unknown authority"}
{“timestamp”:“2025-04-10 02:00:24.017 Z”,“level”:“warn”,“msg”:“Buffer too small for first packet from 172.17.0.1:57212: short buffer”,“caller”:"app/plugin_api.go

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Thanks! I am not sure what you meant by Preview XXL Wine mode. We are having enabled TLS server https call should work in docker preview image. Are you having issue with call in the docker preview image? Could you elaborate on the solution and how to fix the call not connect issue?

“amelia” was a spammer that snuck through.

How did you instantiate your docker container? Did you use our docker compose file? If you ran a docker command yourself, did you pass 8443/UDP in?

I did not use docker compose file. I just issued this command according to the documentation docker run --name mattermost-preview -d --publish 8065:8065 --publish 8443:8443 mattermost/mattermost-preview
Is that correct or should I include the port?

Is there a docker compose file I can use?

Honestly, I wouldn’t use docker. It’s great to quickly stand up a proof-of-concept or demo, but you’ve already spent more time on this than if you’d just used the tarball. And we definitely do not recommend docker for any production use.

Thank you so much! we’re not running in production. This is for a quick demo of the features. Should the call at least work in the docker preview image at least? Would you be able to tell what might be other issues as to why call is starting but not able to connect?

Have you seen Calls self-hosted deployment - Mattermost documentation

Yes, I saw this link and trying to figure out if there’s anything that we might miss in the configuration. Hardly any ways to troubleshoot this start call connection issue.

If 8443/UDP is open bi-directionally, calls will work. It will try to fall back to TCP if UDP is unavailable, but that’s sub-optimal. Can you use a browser on the same network as the server, connect to Mattermost, and start a call? What does the network topology look like between your server and clients? Anything in between could be filtering that traffic.

Yes, I’m using the same browser on the same network as the server of mattermost. Network topoloy is simple. I got 2 VMs running the mattermost clients (web browser) and they call each other. they’re in the same network with the mattermost server. Nothing in between it. It just initiate “start call” and not connect. I wonder if can capture something in the wireshark to see the problem or is there other log I can view to spot the issue. It should work like you said.

You could open the Developer Console of your browser and track the network traffic and Console output while trying to start a call

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