# Cannot reach extension web server

**URL:** <https://discourse.slicer.org/t/cannot-reach-extension-web-server/25890>\
**Category:** Support\
**Tags:** extensions-manager\
**Created:** [October 25, 2022, 9:56am UTC](https://discourse.slicer.org/t/cannot-reach-extension-web-server/25890 "2022-10-25T09:56:11Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![ferhue](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/ferhue/32/82557_2.png) [@ferhue](https://discourse.slicer.org/u/ferhue)\
**Post date:** [October 25, 2022, 9:56am UTC](https://discourse.slicer.org/t/cannot-reach-extension-web-server/25890/1 "2022-10-25T09:56:11Z")

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Hello, today I was trying to install one extension, but I am unable to access the server. This is the message I get within Slicer’s extension manager:

# Extensions can not be installed.

- Failed to load extension page using this URL: **[@KitwareMedical/slicer-extensions-webapp](https://extensions.slicer.org/catalog/All/30893/linux)**
- Check that **3D Slicer** is properly installed. [Read more…](https://slicer.readthedocs.io/en/latest/user_guide/getting_started.html#installing-3d-slicer)

Try Again

I am using Ubuntu 22.04 and Slicer 5.0.3 stable.

I also tried directly entering from different web browsers the extensions website, to no avail.

Is someone experiencing the same?  
Thanks!

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**Author:** ![jay1987](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/jay1987/32/16183_2.png) [@jay1987](https://discourse.slicer.org/u/jay1987)\
**Post date:** [October 25, 2022, 12:43pm UTC](https://discourse.slicer.org/t/cannot-reach-extension-web-server/25890/2 "2022-10-25T12:43:02Z")

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i meet the problem before and use vpn to solve this problem

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**Author:** ![ferhue](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/ferhue/32/82557_2.png) [@ferhue](https://discourse.slicer.org/u/ferhue)\
**Post date:** [October 25, 2022, 1:23pm UTC](https://discourse.slicer.org/t/cannot-reach-extension-web-server/25890/3 "2022-10-25T13:23:43Z")

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oh, I see… so maybe it’s the same issue as in [New release 5.0.3, unable to download extension - #2 by lassoan](https://discourse.slicer.org/t/new-release-5-0-3-unable-to-download-extension/24524/2)  
Thanks.

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**Author:** ![ferhue](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/ferhue/32/82557_2.png) [@ferhue](https://discourse.slicer.org/u/ferhue)\
**Post date:** [November 7, 2022, 4:16pm UTC](https://discourse.slicer.org/t/cannot-reach-extension-web-server/25890/4 "2022-11-07T16:16:44Z")

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I solved this now by adding 8.8.8.8 and 8.8.4.4 to the DNS nameservers, without having to use any VPN.

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**Author:** ![lassoan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lassoan/32/13_2.png) [@lassoan](https://discourse.slicer.org/u/lassoan)\
**Post date:** [November 7, 2022, 6:14pm UTC](https://discourse.slicer.org/t/cannot-reach-extension-web-server/25890/5 "2022-11-07T18:14:25Z")

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Thank you. These IP addresses are Google’s DNS servers, which are safe to use. Maybe your previous DNS settings were not correct, or the DNS servers were misconfigured (either accidentally, or intentionally - to try to restrict what sites can be accessed).

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**Author:** ![ferhue](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/ferhue/32/82557_2.png) [@ferhue](https://discourse.slicer.org/u/ferhue)\
**Post date:** [November 7, 2022, 6:38pm UTC](https://discourse.slicer.org/t/cannot-reach-extension-web-server/25890/6 "2022-11-07T18:38:32Z")

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Well, the default DNS servers were those from my university (local), so probably intentionally restrictive.