I am afraid this is currently not possible.
In the old version called Map Maker it was possible to select several objects, and label them all in one click by choosing the label icon in the menu bar.
In Network Atlas, this feature has been removed. "Add label" just makes a new unrelated label in the 0, 0 position in the center of the map.
A real pity for us that have maps with hundreds of servers. Glad that we had most of our maps made in Map Maker then ;)