Who faced dns error in isp manager?

Question

Domain Name System

Added www domain site.com, without autosubdomain, then made admin.site.com also without autosubdomain.
Everything was ok yesterday, today admin.site.com started giving dns error. At the same time, www.admin.site.com works.
To be honest, I can’t even imagine where the legs grow from, with such behavior. If anyone knows or at least has an idea where to start - "I will say thank you", maybe twice.