While I have much experience in the old days using AFP with legacy Macs in first, LocalTalk and then EtherTalk networks, I do not have much experience in using OS X Server for file sharing and its setup applications are completely different and much more complicated.
I think this is the source of my problem:
I want my Mac SE/30 to "Appletalk" to my MacMini2,1 to "puddle jimp" to my MacMini running High Sierra and stop having to use SneakerNet.
I am finally successful at getting System 7.5.3 with Open Transport 1.3 and AppleShare 3.7.4 on my Mac SE/30, and my research tells me that it is compatible with AppleTalk up through OS X Tiger 10.4.
I have a legacy MacMini2,1 that has two partitions to boot: OS X Snow Leopard 10.6.8 or Tiger Server 10.4.11.
For some reason, years ago I obtained a full package of Tiger Server and not just the plain-vanilla, Tiger and that is what I have installed for my legacy needs.
I acquired a Farallon iPrint AppleTalk to Ethernet hardware bridge (which will not pass TCP/IP only AFP) and even the proper crossover Ethernet cable on one end and a properly terminated PhoneNet connector on the other.
As you can see in the photograph below, I can now see "MacMini2-1" in AppleShare in the Chooser of the Mac SE/30 but when I attempt to connect as a registered user with password or even Guest, which I authorized, it continuously fails.
I think it must be my inexperience with setting up a "OS X Server" version for file sharing and there must be some box that I am not properly checking, etc., that should make this sork.
All advice is appreciated.