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I’m doing some research to disable the QUIC protocol for Windows computers for Firefox using Intune. I think I’ve hit my limit of google searches and asking Copilot for help.

I’ve pieced together what I can. So far I’ve imported the Firefox templates into Intune but I can’t
find the setting to disable. I’ve looked into using a custom configuration policy and haven’t found the correct OMA-URI setting to input the JSON string I need to disable QUIC.

Here’s the sites I’ve found so far that have pointed me in the right direction.
https://support.mozilla.org/en-US/questions/1435123

Hopefully someone else has done this previously but I’m unable to find what I need.

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I’m not sure how to block QUIC with athe OMA-URI template. If you import an ADMX template, you can use a GPO setting to block QUIC in Firefox with Intune.

https://support.mozilla.org/ml/questions/1408003

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Thanks for the link. I did import the ADMX template provided by Mozilla and when creating a new configuration policy I can see the Preferences for the JSON file. Thank you! Hopefully the test is successful.

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Evan you hit the nail on the head with this one. Once I configured the ADMX template and input the correct JSON values, Intune reports that it’s working successfully. Thank you!

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Why are you wanting to disable QUIC for?

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We’ve got a new security product in place that potentially doesn’t play nice with QUIC.

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QUIC is more than just youtube streams… HTTP3 , Google Services, file sharing, etc. are now using QUIC. Hopefully they will be able to adjust so they can handle/inspect QUIC.

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Hey I’m trying to use Intune to disable Quic in Firefox. I’ve uploaded the ADMX to Intune but I don’t know what to do next. Can you by chance tell me exactly what steps you took to make this work?

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You would create a new policy and create it from a template rather than the catalog. Expand the Firefox settings from the ADMX template that you imported and select Preferences. There you should be able to paste in JSON:

{
 "network.http.http3.enable": {
   "Value": false,
   "Status": "default"
 }
}
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Thank you for your quick reply. I notice Admin templates are retired but I tried “Imported Admin templates”
I selected Preferences (which by the way are marked as deprecated…) and there’s a list of settings I can configure, but none of them seem to be target network.http.http3.enable and I don’t see a place to simply paste json.

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Your patience and help is VERY much appreciated. :slight_smile:
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I finally figured it out. Everyone here is controlling it via GPO (which is what I failed to catch at first). My devices are Entra joined (not AD or hybrid joined) so I can’t set the json via group policy. Instead I figured out I can create a policies.json file at C:\Program Files\Mozilla Firefox\distribution and load the json there.

{
“policies”: {
“Preferences”: {
“network.http.http3.enable”: {
“Value”: false,
“Status”: “locked”
}
}
}
}

Note this has to be encoded in UTF-8, NOT UTF-8-BOM which it seems to default to if I use Notepad. I used Notepad++ and easily changed it to the right encoding from the Encoding tab. I hope this helps someone out there!

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