@Bobats I have the same exact question.

Hi  @Bobats and community, I have the same problem, i try to conncect the doorbell using an AC tranformer with 21va, but i didn't see that i can configure the 24/7 recording, in fact I just see that just the battery power is detected, when i try to configure the alway active mode. Any anwer from TAPO/TP-LINK Support?. Thanks in advance for your answer. 

  @J4v13r 

If you mean how to make the camera record 24/7.oddly enough,I had the same issue or misunderstanding...need to go to that place and schedule it on a day by day . 

As for the chime or lack of bibnwed jumpers or anything. Wire to the transformer and you're gtg ..

  @rudabb Thank you for your response. My main problem is connecting the doorbell to my home's electrical circuit, that is, ignoring the internal battery, so that the doorbell can record 24/7 without quickly draining the battery. With the little information I've found on this matter, I understand that if you don't have an existing doorbell, you can use a compatible transformer that provides the appropriate voltage. For this, I've used one that provides 20V, since the specifications state that a 16-24V AC transformer is required. However, it hasn't worked. It seems that the D225 tapo isn't receiving power, and according to multimeter tests, it does receive at least 20V. There's little information available on how to achieve successful connectivity. I hope I've made myself clear.

  @J4v13r 

Got it. Sorry.

I forgot about my issues at the beginning. I was going crazy.  In my case it was a low quality transformer.  as long, as you said, you are within this voltage range you should be good to go.  I think try another transformer. That worked for me to the best of my recollection. I think the other one was overheating and spiking the power