Hi Rufus Swart!
This worked in same way even in DS 8.6 versions.
Try to rename your computer manually with same hostname 12345678 and check message

You must have at least 1 character in hostname
Best regards,
IP.
Original Message:
Sent: Jan 28, 2025 05:19 AM
From: Rufus Swart
Subject: Configure computer - computer name restriction
Hi,
Did something change for windows hostname configuration?
seems that you nolonger can rename a device with number only.

Our client uses it as kiosk so the terminal has an ID that consists of numbers only, using a powershell script does work is there any reason for the restriction?