Nginx Reverse Proxy

Hello, I’m sorry to hear that you’re experiencing issues with Rank Math on your Nginx reverse proxy setup. To resolve this issue, you will need to add some rewrite rules manually to your Nginx server configuration.

You can add the following rewrite rules to your Nginx server to fix the sitemap issue:

# START Nginx Rewrites for Rank Math Sitemaps
rewrite ^/sitemap_index.xml$ /index.php?sitemap=1 last;
rewrite ^/([^/]+?)-sitemap([0-9]+)?.xml$ /index.php?sitemap=$1&sitemap_n=$2 last;
rewrite ^/([a-z]+)?-sitemap.xsl$ /index.php?xsl=$1 last;
# END Nginx Rewrites for Rank Math Sitemaps

After adding these rules, you’ll also need to flush your sitemap settings. To do so, head over to Rank Math SEO → Sitemap Settings in your WordPress admin area and make any minor changes to the Links Per Sitemap count. Then click the Save Changes button.

If you encounter any issues while adding these rules, please reach out to your server administrator or hosting support for further assistance.

I hope this helps! If you have any other questions or need further assistance, feel free to ask.

Sources:
Why the Sitemap_Index.xml is Throwing a 404 Error » Rank Math
Rank Math Sitemap Issues and Their Fixes » Rank Math
Rank Math XML Sitemaps on NGINX Servers » Rank Math