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Web Viewer fails with "StreamerNoStunResponsesReceived" on NVIDIA Brev L40S instance #6

Description

@tonifranciskovic-insta

I am running into issues with trying to view Isaac Sim.

I have followed the instructions within this repository. Starting by following the "Quickstart Guide", I've done the following:

  1. Deployed an Isaac Launchable NVIDIA L40S instance through Brev:
Image
  1. Ensured that the instance is fully ready on Brev:
Image
  1. Using the URL from "Using Secure Links", I can successfully gain access to the Visual Studio Code dev environment.

  2. Following the instructions found from isaac-lab/vscode/README.md, I start Isaac Sim using
    ACCEPT_EULA=y /isaac-sim/runheadless.sh
    Output: isaac-start-log.txt
    The application reports Isaac Sim Full Streaming App is loaded. and does not exit or crash.

  3. To view the Isaac Sim UI, I copy the URL of the Visual Studio Code dev environment, change the end to '/viewer/', and wait to see the stream. Initially the new tab shows "Waiting for stream...", but after a short while the window displays an error: ERROR Session start failed with error: "StreamerNoStunResponsesReceived"

Image

Output: isaac-viewer-log.txt
The error message remains displayed, even after waiting for 15-20 minutes.

  1. Troubleshooting:
  • Opened a terminal to the GPU Instance, and ensured that the isaac-lab-nginx, isaac-lab-vscode and isaac-lab-viewer containers are all up and running:
Image

All the steps I've taken have been directly following the instructions found in the README's in this repository. Haven't found a solution to this issue yet.

Activity

  1. shanereetz commented on Feb 25, 2026

    @shanereetz
    Contributor

    Hi @Toni-FR , thanks for the report.

    Can you confirm that port 47998 isn't blocked by your client-side firewall?

  2. tonifranciskovic-insta commented on Mar 2, 2026

    @tonifranciskovic-insta
    Author

    Hi @shanereetz , thanks for the quick response.

    I just verified that inbound port 47998 isn't blocked by the firewall. All outbound ports are open as well.

    If it is useful, here is the output that is written to the developer console of the '../viewer/' tab:

    Image
  3. tonifranciskovic-insta commented on Mar 4, 2026

    @tonifranciskovic-insta
    Author

    I have an update:

    I managed to get the Isaac Sim stream visible. At first, I incorrectly verified that TCP port 47998 wasn't being blocked. After opening UDP port 47998 the stream was reachable. We also opened UDP ports 3478 and 3479.

    Now that the stream is visible, we can continue with our work. There are still a few questions that I would like to ask, so I'll list them below.

    • The stream starts off looking good, but the quality quickly becomes muddy, up to a point where the text's of the Isaac Sim UI are unreadable. Is this only affected by the quality of the network connection, or is there a way to "enforce" stream quality?
    • Is there a way to change the resolution of the stream?
    • Can the font sizes in the Isaac Sim UI be changed?
    • We're also trying to view the stream using the Isaac Sim WebRTC Streaming Client. However, we can't seem to make a connection to the server. We're using the Server IP that is shown as the address of the NVIDIA L40S instance in Brev. Is there further setup required in order to get it working? We can see the following output in the Visual Studio Code dev env when trying to connect through the Streaming Client:
    Image

    While the Streaming Client can't make a connection, the stream can be viewed through the '.../viewer/' URL.

    Thanks.

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