Separate mobile URLs plus hreflang: the annotation nobody gets right

Separate mobile URLs plus hreflang: the annotation nobody gets right

Sites that still run an m. subdomain face a double annotation problem. Each desktop page needs an alternate pointing to its mobile version, each mobile page needs a canonical pointing back to desktop, and hreflang has to live on top of that structure without contradicting it.

The rules:

— Hreflang goes on the desktop URLs only, and alternates point to desktop URLs of other locales
— The mobile page carries a canonical to its desktop twin and does not carry hreflang
— The desktop page carries the rel alternate media annotation pointing to its mobile twin

Common breakage: the mobile template inherits the desktop head and outputs hreflang pointing to mobile URLs. Now there are two competing clusters, one desktop and one mobile, and neither is reciprocal with the other.

Honest advice: if you are still on separate mobile URLs, the most effective hreflang fix is to move to responsive design. Every annotation problem above disappears when there is one URL per page. Until then, keep hreflang on desktop and audit the mobile templates for accidental tags.