In Spider-Man: Far From Home, we see that Tony Stark
has left behind an augmented reality security, defense and artificial tactical intelligence system for Peter, called E.D.I.T.H (Even Dead, I'm The Hero).
And as we see further in the movie, quoting from here,
[E.D.I.T.H] allows the user full access to the entire Stark satellite network, which comes with several hundred tactical drones.
Following this answer, it can be assumed that E.D.I.T.H was probably
developed by Stark during the five years time after the snap. The drone network could have been also put in place during the same time as well (otherwise, when could he?).
Considering this, is there a reason why, in Avengers: Endgame Tony didn't think of using
the drone network during the final battle at the Avengers HQ against Thanos and his army?