The AppleTalk Internet Router manual states:
"A Local Net Setup Conflict error is reported if another router
on a network that is directly connected to this router lists a
conflicting network number or range for that network."
This statement indicates that there is another router on the same physical
cable as the AppleTalk Internet Router that is advertising a network number or
range for that physical cable that is different from the network number or
range in use by the AppleTalk Internet Router. The key to correcting the
problem is to locate the routers that are attached to the physical cable with
the problem and verify that they all are using the same network number or range
for that physical cable.