Why is my mobile site failing the Core Web Vitals Assessment?

Topic summary

Multiple users are experiencing failed Core Web Vitals assessments specifically on mobile devices, while desktop versions pass. The primary issue centers on Largest Contentful Paint (LCP) metrics.

Key Problems Identified:

  • Mobile sites failing Core Web Vitals despite desktop passing
  • LCP appears as the main failing metric
  • One user notes confusion as their LCP shows green but assessment still fails
  • Another user questions whether Google Ads might be contributing to mobile performance issues

Suggested Solutions:

  • Focus on resolving LCP issues to achieve passing status
  • Use ranksite.in tool for detailed analysis and improvement recommendations
  • Review expanded LCP component details for specific optimization targets

Current Status: The discussion remains open with users seeking specific guidance on fixing mobile LCP issues. Several screenshots were shared showing the failing assessments, though technical details about root causes haven’t been fully explored.

Summarized with AI on November 10. AI used: claude-sonnet-4-5-20250929.

Recently Page Speed tester has shown Core Web Vitals Assessment as “failed”. This problem is only on Mobile side and desktop seems to be ok.

Can anyone tell me what is wrong / causing this, and how to fix it?

Website: https://pawsson.fi

@Pawsson ,

If you will solve issue of LCP, (It will result in Green) then your Core Web Vitals Assessment as pass.

One thing I have seen the LCP is in green already.

1 Like

You can check https://www.ranksite.in it can help you in improving the score for mobile and desktop devices.

Hi, I have a Facebook Video Downloader. But I’m getting mostly traffic from Facebook Photo Downloader. My Desktop Core Web Vital is passed but on mobile, it’s failed. Is it because of Google Ads or any other issue? It says LCP but it doesn’t seem what it shows. I remember that before this much traffic (33K per/month) speed was good enough but what happens now? How to fix it?

Hi there, can you please share the expanded view of your LCP component, also you can login on https://www.ranksite.in to generate a free report detailing about fixes and improving core web vitals.

Thanks