I fall on this topic as I'm wondering what cause the same weird behavior on my brand new (sole) 4K camera. Dahua's doc mentions that this message ("lack of ressources. Video failed.") indicates there is a lack of bandwith.
So I've replaced the small toy POE switch (which was working fine with a Hikvision 4MP camera...) with a Linksys 24 POE+ Ports (that I already owned, naturally). Same behavior.
It's suggested to reduce the resolution. Slightly better but not yet perfect. Encoding was reviewed, sub stream is deactivated. No DVR here, the camera web interface lags even when I do not stream it...
I'm surprised to read that
CAT5e is "enough". Cause that was my guess, as I'm not sure that this behavior was encountered when I was configuring/testing the camera, whilst on the table, powered-up at that moment by a dedicated power supply...
This is also weird as the previous camera was working fine, with the same network cable.
I'll have to unmount the camera to definetely have a good idea on what happens exactly. "Underpowered" because of the cable, power or bandwith greedy (can't imagine)...