Hello A.,
Network and server must be declare as ID (without "-" or "_",...), but here is a possible workaround, you can use description, as:
@startuml
nwdiag {
network NW_5012_VM6SW {
description = "5012-VM6SW";
width = full
dev_A [address = "dev_A" ]
dev_B [address = "dev_B" ]
}
}
@enduml
See similar request, for server name, here:
If that can help,
Regards,
Th.