Turn off HTTP/3 on Cloudflare: Cloudflare’s proxy might be forcing HTTP/3, which Gandi’s DNS setup may not handle smoothly. Disabling HTTP/3 in Cloudflare (temporarily) could help pinpoint if that’s the issue.

SSL Mode: Ensure Cloudflare is set to “Flexible” SSL for now, as you don’t have certs on your load balancer. This can avoid SSL mismatches.

Flush DNS: Set a low TTL (1 minute) for both domains, then flush your DNS cache. This helps if stale records are interfering.

Check Load Balancer Logs: See if requests from www.g-example.com even reach your load balancer. If not, the issue might lie with DNS routing between Cloudflare and Gandi.