Itunes sees, but won't load other user's shared library I'm stumped.

My computer, Lothlorien, shares my iTunes library to the local network.

My wife's computer, Gutenberg, can 'see' my library in the drop down ribbon top left (Music...) but if she selects it, there is a spinning icon for about 20 seconds, then it pops back to her normal view.

The book keeping computer, Fibonacci, can see and load the library on Gutenberg, but doesn't even see Lothlorians.

Lothlorian's console shows:

2019-05-18 8:21:10.864 PM com.apple.xpc.launchd[1]: (com.apple.imfoundation.IMRemoteURLConnectionAgent) The _DirtyJetsamMemoryLimit key is not available on this platform.

2019-05-18 8:21:11.185 PM com.apple.iCloudHelper[68679]: objc[68679]: Class FALogging is implemented in both /System/Library/PrivateFrameworks/FamilyCircle.framework/Versions/A/FamilyCircle and /System/Library/PrivateFrameworks/FamilyNotification.framework/Versions/A/FamilyNotification. One of the two will be used. Which one is undefined.

2019-05-18 8:21:11.192 PM com.apple.xpc.launchd[1]: (com.apple.imfoundation.IMRemoteURLConnectionAgent) The _DirtyJetsamMemoryLimit key is not available on this platform.

2019-05-18 8:21:11.566 PM com.apple.xpc.launchd[1]: (com.apple.imfoundation.IMRemoteURLConnectionAgent) The _DirtyJetsamMemoryLimit key is not available on this platform.

All three computers are running Yosemite current.

The errors were logged within seconds of attempted access (I can't be at two machines at once...) and were similar for each attempt.
The errors you cite doesn't necessarily have anything to do with the problem you're encountering. 10.10 (Yosemite) is nearly five major OS revisions old now... I assume being run because your machines no longer support newer operating systems?

All I can really suggest is that you make sure each of the machines are running 10.10.5 and all supplemental updates, and all have the latest supported version of iTunes installed, 12.8.1.