Brother HL-4040CDN - Manual (Page 152)

Security features
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12
j
Click Yes, if the fingerprint (thumbprint) is correct.
Note
The fingerprint (thumbprint) is printed on the Printer Settings Page. To learn how to print the Printer
Settings Page, see Printing the Printer Settings Page on page 116.
k
Click OK.
l
Now the self-signed certificate is installed on your computer, and SSL/TLS communication is available.