L&LD
Part of the Furniture
The use of the firmware's built in ntp server isn't relevant. If the ntp script of @Jack Yaz requires the use of host names then simply set the caching setting to yes. I don't understand the complexity here. Sorry.
You may have missed this then.
https://www.snbforums.com/threads/384-12_alpha-builds-testing-all-variants.56639/page-16#post-494084