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Surveyor II

Trouble for some Comcast Users of Canvas

Please check with your User Support/ Helpdesk staff to see if any of your users are suffering from this issue that may go undocumented as home PC or browser issues. This issue appears to be a Comcast/Xfinity customer issue involving Comcast's DNS.

We had multiple users over a period of days report receiving a specific error when attempting to get into Canvas. The error was that the connection to was not secure and that there was an issue with the certificate.

259073_Your connection is not private.png

259060_Certificate error Fake Cert on

We have a vanity URL and we authenticate through single sign on. The problem would occur if the users were already authenticated or still needed to authenticate.

After several days of troubleshooting with no resolution we were told this likely was an issue with Comcast, the ISP. 

We contacted other Colleges in our area since our students may share the same Comcast internet service providers and we were immediately told that not only had they suffered the same issue but that another University in the area suffered with this issue for a month before they finally had it resolved with Comcast. I'd like to thank Joliet Junior College for assisting us with this valuable and hard earned information, they and another local University were instrumental in bringing this information to you. Without their information we would still be asking Canvas for support and asking our users to reset their browser cache with no resolution.

Our trouble is ongoing. and we hope to have a solution from Comcast soon. I'd hate for you and your users to suffer through a week or month of being asked to clear browser cache and flushing DNS cache only to find out you have to contact Comcast and still wait additional days for a resolution. Our Comcast ticket was opened on Friday and is still not resolved.  Here are the relevant case numbers:

Canvas Case: 02573797

Comcast Case numbers: 

First one: CR742676296

Second one: CR743243533

And Comcast DNS Support – the ticket # is #7110  << from Joliet Junior College who gratefully shared their history with this same issue.

When contacting Comcast it appears to help to describe that you are reporting an issue of their customers getting to Canvas LMS a Learning Management System site. That you were informed that other colleges and universities  had similar issues with Comcast DNS caching old information/addresses and that Comcast was able to clear this issue from it's back end servers.

You will want to provide Comcast with the web addresses particular to your institution, your non-vanity address and the address if your trouble is as described above:


and your vanity address (ours is

We hope this resolves your issue but our own issue is on going. If anyone has had a positive outcome on this same issue with Comcast or another ISP please share your advice with the community. We all would appreciate this.

My hope by sharing this information is that your users will no longer have to suffer thinking it's their PC and browser and that as a community we can get Comcast to correct this issue for everyone. 

Scott Leturno

LMS Administrator 

Moraine Valley Community College

Edited 11/07/2017 to Acknowledge Joliet Junior College for their experience shared on this issue. I'll only share the name of the University with their permission but both of the schools were key in identifying how we needed to address this with Comcast.

33 Replies
Community Coach
Community Coach

THANK YOU!! We’ve been having the exact same issue and will be contacting Comcast directly this morning. 


I hope this helps. At least we can all start moving in the same direction for a resolution.

Community Coach
Community Coach

As an update, I just finished chatting (virtually) with Comcast/Xfinity support and they are apparently aware of the issue and working on it. Overall it was a pretty easy conversation and I had no arguments from them about the issue... I'm assuming because I had so much information - thank you!! My case number is CR743397625. 

For others going through the issue, I contacted Comcast/Xfinity through their online chat - - I selected Internet support and then guest, and provided this exact wording (you would want to add my case number to this):

I am the Director of Online Learning at Richland Community College and am reporting an issue with a large number of my students and faculty who use Comcast/Xfinity accessing Canvas LMS, a Learning Management System site. We have been informed that other colleges and universities had similar issues with Comcast DNS caching old information/addresses and that Comcast was able to clear this issue from it's back end servers. 

Here are the effected web addresses - & 

Here are related Comcast Case numbers - CR742676296 & CR743243533 - for others experiencing this issue.


I tried this and didn't have any luck.  This is exactly why people are always posting the audio of their Comcast calls on the internet.

I also gave the rep the ticket numbers and she said she couldn't find anything, ugh.

Any suggestions?

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Try reporting the problem from their online form or chat. Just a suggestion.

Community Coach
Community Coach

Sorry, I just saw this! I would recommend the chat option. It seemed to work quite well and they didn’t have a problem finding this information. As a side note, even though our students don’t seem to be having this problem any longer, I’ve never officially heard back from Comcast on it. 


Comcast is not in our area, but this is the type of information that is extremely helpful to the community.   Thanks.


I just wanted to share a theory about the cause of this issue that could be helpful to others. Our problem began on or around the anniversary date of our Canvas instance being created, September 16th, 2013. My theory is that some type of certificate renewal on AWS occurred on this day (yearly expiration) which removed some existing addresses. These addresses are still cached within Comcast's system and are no longer a match with the certificate. Can any of you that have run into this issue verify that you started receiving calls on or around your anniversary date?


This issue also highlights a possible need/benefit for Canvas to have representatives assigned by geographic region.  Our rep. meets with us monthly but is not the rep. for our nearby schools/colleges.  If one rep. were over all schools/colleges in the area he/she would hear that multiple institutions were having the same issue and hopefully be a conduit of communication/information sharing amongst them all.  It is simply by chance that we made initial contact with a local university who was having this same issue, simply by chance that the poster of this posting/institution reached out to us, and simply by chance that Kona/Richland saw this post.  With a common rep. we may have arrived at this knowledge much sooner.  Just a thought/idea for Canvas to consider.

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