Duets no longer find library!

[kidpocono]

I've got 4 Duets, all connected via Ethernet to my MacMini which runs LMS 7.7.7
(I'd been using 7.5 since in the past I found that upgrades would often cause issues
with the older 10.5.8 system on this model). I'd had 3 of them set up fine without
issues for many months. In installing the most recent one, though, I've encountered
a problem.

My two initial Duets work fine, but the later two now cannot locate the server/library.
I have restored factory settings and reset the receivers several times. The Advanced
settings show that the MySqueezebox account is running fine, but in Diagnostics,
neither shows the library. On the two that work, the Library shows with the name,
not a number, so I cannot input it on the screen with respect to manually setting
where I suppose the software should look for the library.

I've reset the router to which all cables are connected, since other threads imply that
it is usually a network problem, but as noted above, 2 work and 2 don't. On the problem
ones, I am indeed able to access Internet Radio just fine, so I can't understand how the
network can be an issue and why these two cannot "see" the server and library.

Is there anything I can do to force these to "find" the library, which works just fine
on the other two Duet receivers?

Thanks much! Paul

[kidpocono]

I should also mention that the two Duets that no longer connect had each been
cabled to an Ethernet splitter, which caused me to think that somehow the two
"confused" the LMS system.

To see if this was the case, I decided to connect the most recent one by
WiFi and not the Ethernet, but the same result happened. The 3d one,
which remained attached to the splitter, still has that problem as well.

Both of the first 2 Duets are also attached to splitters, but different ones,
and each of the splitters is connected by Ethernet directly to the router.