Hello @RobGreig - my first thought was that the instructor may have copied content from a prior course and for some reason the link wasn't updated. But then you have noted that the phone shows the sign in page (but can you sign in and view the content?).
For the computer, check the web browser settings. So you have blocked third party cookies blocked by chance? Try allowing them for and reload the page.
===========
Chrome
For Canvas you need to “allow all cookies” on Google Chrome to have different tools work properly. Follow the outlined steps or visit the Chrome guide.
- On your computer, open Chrome.
- At the top right, click More (the three dots) then > Settings (the gear).
- Under “Privacy and security,” click Cookies and other site data.
- Select an option: Allow all cookies.