Can CDN services or web application firewalls (WAFs) cause a 403 error for a WordPress site, and how to address it?

Yes, CDN services like Cloudflare or WAFs like Sucuri can sometimes cause 403 errors. These services act as a proxy and apply their own security rules. If they detect suspicious activity, an unrecognized IP address (especially for new server setups), or a rule is triggered incorrectly, they might block access with a 403. To address this, check the WAF's activity logs for blocked requests, review and adjust its security rules, or temporarily pause the CDN/WAF service (e.g., Cloudflare's 'Development Mode') to see if the error disappears, then reconfigure accordingly.