Hi @rsavelkoul,

If you have more than one login provider, you'll probably want to create and configure a "discovery page" for your Canvas instance.  This webpage would list all of the login providers you have and allow users to click on the correct one for them.  When you configure this in the Canvas authentication area, it will redirect all users to the discovery page to login, which should solve your issue.   Here's an example discovery page, which my institution uses: https://umdearborn.edu/canvas/professional-development-canvas/professional-development-canvas-login.

Hope this helps!

-Chris