I know Fly terminates TLS at the edge and sends the unencrypted plaintext to my app.
Yes, all comms on Fly’s backhaul is encrypted with WireGuard (ref).
Is the fly internal network encrypted?
Note, internal network between two apps in the same Fly org (6pn) is also on Fly’s WireGuard backhaul: 6PN addressing clarification - #2 by kurt