Hello,
Thank you for contacting us and sorry for any inconvenience that might have been caused due to that.
We tested the website with our external SEO Analyser and the site is showing an invalid response from the server as shown below:

Please get in touch with your host and ask them to whitelist the IP 46.30.211.100
and the user-agent RankMathApi/2.0.7; https://rankmath.com
and see if that works for you.
For more details on this issue, please check this guide: https://rankmath.com/kb/api-http-400-error/
Hope this helps, and please do not hesitate to let us know if you need our assistance with anything else.
Thank you.
Hello,
Since we did not hear back from you for 15 days, we are assuming that you found the solution. We are closing this support ticket.
If you still need assistance or any other help, please feel free to open a new support ticket, and we will be more than happy to assist.
Thank you.