Hi,
i report the SV B01 3MP POE as functional.
Gateway (Raspi)
Digest
264 -> Note that the cam is setup to this parameter; my cam was set to 265 at beginning
G711
rtsp://…IP…:554/stream1 -> Echo5 can´t handle 3MP(stream0) set stream1 to VGA resolution
1024x576 -> 16:9 i haven´t try VGA for this setting.
Tags noaudio + proxy I havent tested more or less.

Please check the gateway logs - my gateway hang one time

@chrisb306 check any firewalls and disable to test, see my post as got another hik working now with gateway.
Also ensure substream is set to lowest res.