So, not all 'cut the power' missions have the objective of destroying the power plant, despite the wording 'destroy the power plant attached to x'
Some require you to scan a control point which, frankly, can be named anything. This causes the 'power generator' whatever that is to detonate.
The thing you scan might not even be called comms relay hub, and could be called something like 'network hub' or something.
Personally i think having a mission whose objective wording is to destroy something, when in actuality you have to scam something *to cause* the destruction is confusing design, especially when done of those missions work the same wording require you to actually blow something up.