This is for a client site. Google seems to only return mobile results for all search queries. The m. and desktop site are not competing or conflicting with each other however..
All m. pages have the correct canonical (absolute URL) pointing back to the www. version.
And every www. version has the correct rel alternate (absolute URL) pointing to the m. version. Using the media value media="only screen and (max-width: 640px)"
Pages are delivered by CDN so vary is not being used in the HTTP header, but the pages are not that responsive or adaptive.
Both versions of the site are being indexed by Google and fetching the page works as expected.
The hreflang elements use relative URLs, can't see this being the cause.
Some have suggested it is a DNS issue, but also can't see how that would affect it.
Anyone have any ideas?