# \[notes\] CDN problem on umich.edu eduroam network

**URL:** <https://discourse.slicer.org/t/notes-cdn-problem-on-umich-edu-eduroam-network/88>\
**Category:** Admin\
**Created:** [April 12, 2017, 9:05pm UTC](https://discourse.slicer.org/t/notes-cdn-problem-on-umich-edu-eduroam-network/88 "2017-04-12T21:05:33Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![ihnorton](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/ihnorton/32/9_2.png) [@ihnorton](https://discourse.slicer.org/u/ihnorton)\
**Post date:** [April 12, 2017, 9:05pm UTC](https://discourse.slicer.org/t/notes-cdn-problem-on-umich-edu-eduroam-network/88/1 "2017-04-12T21:05:33Z")

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Some users at University of Michigan cannot access the Discourse CDN for some site resources. Here’s a debugging conversation (I followed up by email up from [this topic](https://discourse.slicer.org/t/problems-to-connect-to-the-discourse-forum-from-uofm/85/4)).

They can’t connect to these other Discourse sites either:

> [https://talk.jekyllrb.com/](https://talk.jekyllrb.com/)

They see a browser error loading resource, and can’t ping the CDN. Does this ring any bells?

* * *

(user):

> On my side, I tried with Safari and Chrome and I have the same result. I can open [discourse.org](http://discourse.org) and the other hosts I tried.

> What happens is the web page loads first the text in a browser tab:  
> ![](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/1X/3524fa7d7ead9e1ed58d19d6d945008e917dd961.jpg)  
> Then the page stays blank and after few minutes it sends a timeout error in the chrome console:
> 
> ![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/1/6/160c8eb409902c3a24de47572b58373772da390b.png)

* * *

(me):

> Ok, that helps to narrow it down a little bit. Can you ping [discourse-cdn-sjc1.com/standard2](http://discourse-cdn-sjc1.com/standard2)? Is there any ad-blocker installed on these computers? There’s a bug report that sounds kind of similar, where some software was blocking the Discourse CDN due to false positive:

> [Discourse CDNs are blocked by privacy badger - #17 by vi0oss - site feedback - Discourse Meta](https://meta.discourse.org/t/discourse-cdns-are-blocked-by-privacy-badger/17127/17)

> Might be happening on your network if they use a similar heuristic or list.

* * *

(user):

> That ping is not working.

 ![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/e/a/ea9eb204e7e6963ee6fc0e868a575e2784ed77ab.png)

> There is an ad-blocker in my Chrome but not in Safari, and I tried to disable the ad-blocker and the issue is still the same.

> Then, why can I access the website with my smartphone on the same network, would it be linked to the browser?

* * *

(me):

> Since you can’t ping the CDN at all, it’s probably not the browser. That seems like it might be a block at the institution level (since you said multiple computers), or at least local firewall.

> I think the ones I originally linked are mostly business hosting, so they might be hitting a different CDN. Can you try these, they’re on the same plan as Slicer and hits a similar CDN for me:

`https://talk.jekyllrb.com/`  
`https://discourse.ros.org`

> > Then, why can I access the website with my smartphone on the same network, would it be linked to the browser?

> Assuming you are connected to wi-fi, but also have cell service, maybe it falls back to unblocked cell network if a request fails – I’m not sure what the request resolution rules are on various phones.

* * *

(user):

> When we tried on laptops, we used eduroam, so not really specific. But, on the computers plugged on the department wifi it’s working fine.

* * *

(me):

> Ok I missed that the first time: so just to clarify

> - the problem is only on the wifi network called eduroam?

> - the regular university wifi works ok? – I guess that would be MWireless and MGuest (from here: [WiFi / U-M Information and Technology Services](http://its.umich.edu/enterprise/wifi-networks/wifi))

> I think you need to contact the university IT in this case – looks like “4HELP@umich.edu” (from the site above). I don’t think there is much Discourse can do if the CDN is blocked on that specific wireless network. From what I can tell, eduroam is just an authentication provider, so university IT controls the configuration.

> It looks like someone else saw weird issues with eduroam too, but no follow-up on any resolution:

> [https://meta.discourse.org/t/mobile-clicking-create-new-account-causes-processing-spinner-icon-to-keep-spinning/55508/15](https://meta.discourse.org/t/mobile-clicking-create-new-account-causes-processing-spinner-icon-to-keep-spinning/55508/15)

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<div class="post-metadata">

**Author:** ![ihnorton](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/ihnorton/32/9_2.png) [@ihnorton](https://discourse.slicer.org/u/ihnorton)\
**Post date:** [April 12, 2017, 9:16pm UTC](https://discourse.slicer.org/t/notes-cdn-problem-on-umich-edu-eduroam-network/88/2 "2017-04-12T21:16:00Z")

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(user):

> I tried with MWireless and eduroam =\> not working but with MGuest =\> working. So, the solution is to contact IT or to switch to a non-blocking network to access the discourse.

So, they are going to follow-up with university IT, because there is nothing we or Discourse can do about local network settings.