Repeated login redirects usually indicate cookie or session issues.
This often happens when site URLs don’t match exactly, especially after migrations.

Check siteurl and home values in the database or Settings → General. Even an HTTP vs HTTPS mismatch can break authentication cookies.

Security plugins and server-side caching can also interfere by blocking cookies or caching login pages. Temporarily disabling those helps isolate the issue.

A frequent mistake is updating URLs in wp-config.php but forgetting database values.
The practical takeaway is to always verify URL consistency across config, database, and server.