seo – Google is de-indexing our desktop site after launching a separate mobile site with fewer pages

For pages where you have desktop and mobile versions of the page:

  • In you example.com page, put a canonical pointing to the example.com page and a alternate pointing to the m.example.com page.

  • In you m.example.com page, put a canonical pointing to the example.com page.

For pages where you only have a desktop version:

  • In you example.com page, put a canonical aiming at example.com page and do not use a alternate label (because there is no alternative representation).

  • Leave your m.example.com Page non-existent.

This configuration ensures that Google will always index your example.com pages as canonical pages and they will not be confused and will index any m.example.com pages, because you will see them as an alternative resource representation.

When a visitor visits your example.com page, detect if they are on a mobile device. If both are on a mobile device and you also have a mobile representation of the page you are viewing, redirect them to the m.example.com Version of the page.