Jesper Hartvig

The DNS is (Often) managed where your domain is hosted.

Are you able to reproduce the error if you do the same as the client?

If not, try and find out what browser and device they are using.

From Bluehost:

We do offer complimentary backups for our customers. They are created on a daily, weekly, and monthly basis. These backups are not guaranteed in any way. We highly recommend that all Bluehost customers create and manage their own backups.

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They should be able to help you.

danyzas is correct. I would like to add the question: What hosting provider are you using?