Previous posts link broken only in Archives

The function nav_posts_link doesn’t seem to be working properly in my archives (works find in Main Index with same code).

If you go to one of my monthly archives, scroll to the bottom then try to see the next page of posts by clicking “Older posts” it takes you to a 404 page. Example: https://summertomato.com/2009/11/

Not sure how to fix it.

Thanks for your help ??