The most common cause of a failed connection is a security plugin blocking Application Password authentication.
Wordfence: Wordfence → Login Security → Settings → turn off “Disable XML-RPC authentication”. OR Wordfence → Tools → Allowlisted IPs → add your home/office IP.
Solid Security (formerly iThemes): Security → Settings → Configure → WordPress Tweaks → set REST API to “Default Access”.
Sucuri WAF: Allowlist your IP under Firewall → Settings → Whitelist URL or IP.
WP Cerber: WP Cerber → Hardening → disable “Block access to WordPress REST API”.
Hosting-provider firewall: Some managed hosts strip the Authorization header. Contact support and ask them to enable Authorization-header passthrough for Application Passwords.