Ok bought this from amazon (Empiretech) and it worked fine at initial setup (plugged straight into TP-Link PoE switch). Initial install was easy (BI). After that however, it won't power up again with just PoE. Seller suggested testing with 12v 2a plug, and yes, that works. Removing the 12v after successful power-on works too and it can sustain itself on PoE just fine. But it won't
start up with PoE alone for some reason (actually, sometimes it does, after 10-20 minutes). Tried upgrading to PoE+ switch (even though the specs for cam don't require that), and same result. Neither
cat5 or cat6 make a difference.
I don't have much experience with this brand (mostly have Hikvisions), but I really like it so far (from when I got it working). Seller also suggested using Dahua-branded NVR to connect... surely that's not necessary..?
Edit: found a 12v extension cable and "jump started" the camera.