After a lot of research I decided on (1) a Raspberry Pi, a (2) 5tb Hard Drive and an (3) an old router I wasn’t using.
Works great offline after initial setup online and adding the local IP address range as shown in the article shared by @Insomnic_1.
This is exactly what I bought from Amazon:
Raspberry Pi 4B Full Official Desktop Computer Starter Kit $110: https://amzn.to/3gTgxEF
WD 5TB Elements Portable External Hard Drive $99: https://amzn.to/3vZS4SA
Hope it helps,
Shawn