Hi machols,
I understand you would like to set up your SharePoint website and continue to point to the current hosting provider. From the error message, the IP Address you typed should be the address where your website is currently hosted, for example: 172.16.140.1. You can contact your DNS hosting provider to verify the proper value of IP address.
In addition, this online article provides detailed steps for your reference: Update DNS records to keep your website with your current hosting provider
Thanks,
Maggie Li