1080P PoE Video Doorbell (SD-M5) Issues

[Vincero]

I'm testing the Tuya version of the Yoosee SD-M5 - product page:
1080p app controlled smart doorbell camera PoE wireless Wi-Fi AC 8-24V DC 9-36V built-in PIR motion sensor Tuya door phone (tuyaoem.com)

I've run in to some issues when trying out some of the functionality:
Tested on Wireless mode only so far (testing on ethernet I will do later):

• It is unable to connect to WiFi networks where the SSID is hidden
  Using the Tuya app, specifying the WiFi network, getting the QR code to provide the camera and getting the acceptance chirp from the camera function as expected however the doorbell never successfully joins the network.
  As even WPA2 is vulnerable to a key derivation attack given enough time when the SSID is known and broadcast (and you would expect the WiFi network passkey settings not to change for a long period), not being able to be used with a blank SSID is a potential security hole.
  
  When set to use a WiFi network with SSID broadcast enabled the device connects normally.
  
  
• On Android: When ringing the doorbell, the call comes through to the phone but the picture snapshot 99% of the time doesn't seem to function and is never retrieved.
  
  It remains at 'Loading Image...'
  
  Once the call is 'answered' (green button) the phone remains locked with audio only. This may be handset specific. I have yet to test iOS or on maybe an Amazon Fire (still essentially Android) device.This occurs regardless of being on the same WiFi network as the doorbell, or on 3G/4G or on another WiFi network.
  In terms of WiFi signal, the doorbell is not installed on a wall outside of the building, it is being tested in the same room as the WiFi router/AP.Is there potentially some port / firewall setting that needs to be set or another function enabled on the router/firewall (some for example have a VOIP/SIP compatibility mode, etc.)?
  
  
• The doorbell is constantly broadcasting to the network subnet (using a send to IP 255.255.255.255) a UDP packet on port 6667 to all devices.
  What is this for? This would only be for the doorbell device to try to communicate with local network devices - any (good) router should ignore/drop these packets and not send to internet. After checking other online sources this seems to be a common IoT device thing.
  Is there a list of ports / TCP functions used by the device?

Is there some way of viewing a log or debug to see why the snapshot image on doorbell ring is not brought through?

Thanks.