Hi all scratching my head with this 

purchased the c501 use it with POE works fine on house internet won't work when not on the house broadband band- can only be controlled locally. Have contacted support the advised turning off parental setting on our router this made no difference I also disabled firewall again no difference. Cannot update firmware on the camera as it says network unstable. 

The camera is connected to a linkys Ethernet poe switch. We also have an internal camera Tc70 connected WiFi to an access point connected to the same Poe switch which works fine viewing remotely when away from house. Both cameras are on the same Tapo account along with various smart sockets that all work fine remotely.

Tapo support advised we purchased a replacement camera as the first one could be faulty but as I suspected it's exactly the same. Something dome where is stopping the camera talk to the outside world. Have read some articles about changing DNS settings on the router but we cannot do this. 
seems strange the WiFi camera works fine Poe not ! 
We are on  BT fibre 

Using memory card inside the camera, don't think that makes any difference 

I would like to get this working as I like the Tapo interface would like all my smart devices on one app 

thanks