Translation.
THE PRINCIPLE
Explain the effect and the fix, not the mechanism.
WHAT CLIENTS WANT TO KNOW
Is it fixed? Will it happen again? Do I need to do anything? Did I lose anything?
WHAT THEY DO NOT WANT
An explanation of DNS propagation Details of server configuration The technical cause
EXAMPLES OF TRANSLATION
"Your DNS records were pointing at the previous host" becomes "your domain was still directed to your old hosting, which I have corrected."
"The account exceeded its entry process limit" becomes "your site was receiving more simultaneous visitors than the plan allows, which caused the errors."
WHEN TO GIVE DETAIL
When they ask for it When they are technical When they need to change their own behaviour
WHAT TO ALWAYS INCLUDE
What they must do, if anything.
WHAT TO AVOID
Making them feel foolish Implying the question was obvious
WHAT TO OFFER
A link to documentation, for anything they may need again.