I've done some test, on my DS-7216HQHI-K1 DVR with 3 different 2 way audio capable IP Cameras:
- DS-2CV2021G2-IDW (E) - E8 Series camera
- DS-2CD2420F-IW - R2 Series camera
- IPC-B120HA-D-W-(W)
but non of them worked when accessed via DVR in Hik-Connect.
Also, all of them worked just fine when added individually on Hik-Connect.
So, I guess 2 way audio is not available via DVR . . .