Duplicate pages without canonical

Hello,

I have an issue for my WP site. I am not sure this is the right place to ask but hopefully someone here will be able to help me.

I use Ahrefs for monitoring my Site Audit.

This is an error message Ahrefs gives me: “Duplicate pages without canonical”

The problem is that I have 1.192 results and for each one of these, a number of pages having the same content.

It’s not too easy for me now to manually add the rel=”canonical” to literally thousands of pages.

1. Is there any easier way to fix this than manually add the rel=”canonical” to thousands of pages?

2. Why is this happening to my site?

3. Should not WP be able to automatically take care of this so I won’t find these issues later?

Example 1:

url: https://www.neotel2000.com/2019/08/

No. of pages having the same content: 5

This page
https://www.neotel2000.com/2019/08/
Canonical Missing

Pages that have duplicated elements:

Page
https://www.neotel2000.com/que-ventajas-tiene-y-que-significa-la-marcacion-automatica/
Canonical
https://www.neotel2000.com/que-ventajas-tiene-y-que-significa-la-marcacion-automatica/ (Self-reference)

Page
https://www.neotel2000.com/tag/marcacion-progresiva/
Canonical
https://www.neotel2000.com/tag/marcacion-progresiva/ (Self-reference)

Page
https://www.neotel2000.com/2019/page/3/
Canonical (Missing)

Page
https://www.neotel2000.com/tag/sofware-de-marcacion-de-llamadas/
Canonical
https://www.neotel2000.com/tag/sofware-de-marcacion-de-llamadas/ (Self-reference)`

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