Iron Router Error in in IE 11

Hi There

I am having some issues with my Meteor app in Internet Explorer 11.

I am not able to replicate the issue myself, but a client is reporting that they are getting an Iron Router error when trying to access my app:

Has anyone seen this before or any idea how I might be able to resolve? I am able to view the app using another Windows 10 machine with the same version of Internet Explorer 11.

Thanks

This is 100% anecdotal, and also from ~2 years ago, but I remember seeing this when I had issues that were completely unrelated to iron router. Console logs from your client would probably be the most helpful thing at this point?

Thanks. I have made an appointment to meet the client at his house this evening to see if I can resolve from there. Its such an odd error.