Hey John,
The reason you are getting the "your connection is not secure" error is because your url contains https. Refer to this: https://www.healthmaxphysio.com/

Since that website did not configure a secure http certificate, you would not need https to access the website. If you change your url to http://www.healthmaxphysio.com or http://www.healthmaxphysio.com I believe the link will be working as it should. Give it a try and let me know how it goes. Cheers.

I've tried it both of the ways suggested above, but still get the error.

Hey John,

I believe there could be a plugin that is replacing http -> https and this is most likely the case for the post at https://www.torontohiking.com/tohi/blogs/guest-blogs/entry/5-tips-to-prevent-injuries-while-hiking.html

If you are aware of such plugins, could you try turning that off temporarily?