How do I get the app to recognize the cameras

[E_C]

I have several cameras. All of them can be seen by my router. But NONE of them can be found in the Arlo app to be connected.  
How do I get the app to recognize the cameras, when I know my router sees them? 

[jguerdat]

Are you selecting the proper model when trying to onboard them? There's a difference between the Essential camera and the Essential spotlight camera so you have to make sure you're choosing the right version.

You can also try resetting them:

https://kb.arlo.com/000062438/How-do-I-factory-reset-and-re-sync-my-Arlo-camera