Hello A., and all,
Here are some proposals, if one suits you...
@startuml
nwdiag {
network net {
fw1 [description = "<&grid-three-up*4>\n fw01"];
fw2 [description = " <:fire:><:bricks:>\n fw02"];
fw [description = " <U+2632>\n fw03"];
s;
}
}
@enduml

Regards.