Why am I getting 403 errors on my Webflow site, but only when I try using my Ionos domain?

You're seeing 403 Forbidden errors on your Webflow site when using an Ionos domain because the domain or DNS settings are likely misconfigured, especially with A records or forwarding settings.

1. Check Your Domain's A Records

• Log into your Ionos domain DNS settings.
• Ensure you have two A records pointing to Webflow’s hosting IPs:
• (a) 75.2.70.75
• (b) 99.83.190.102
• Each A record should be assigned to @, which represents your root domain (e.g., example.com).

2. Remove Ionos Web Forwarding or HTTP Redirects

• Ionos uses a feature called Web Forwarding, which can override DNS and cause conflicts.
• Disable Web Forwarding or redirection settings in your Ionos control panel, especially if it’s set up for HTTP redirects (i.e., from www.example.com to example.com or vice versa).

3. Add www CNAME Record for Subdomain Support

• Make sure you’ve added a CNAME record for www:
• Name: www
• Type: CNAME
• Value: proxy-ssl.webflow.com

4. Set the Correct Default Domain in Webflow

• Go to your project in Webflow.
• Click Project Settings > Hosting.
• Under Custom Domains, set either the root domain (example.com) or www version (www.example.com) as the default domain using the star icon.
• Webflow recommends setting www as default, as it better supports SSL.

5. Publish to Connected Domains

• In your project, click Publish.
• Make sure you're publishing to both example.com and www.example.com.
• If only one of them is selected, the other will not show your site.

Summary

A 403 error from your Ionos domain usually means your DNS or forwarding settings conflict with Webflow's hosting setup. Ensure your A and CNAME records match Webflow’s requirements, disable Ionos web forwarding, and verify the default domain is correctly set and published in Webflow.