The first link there is another thread of mine!
Haha didn't see that.
Regarding the power setting, is your regulator powerful enough? The standard Arduino regulators usually aren't...
In the past I've had connection problems with some of my modules, and it seemed the signal deteriorated after some years. Now I've placed a repeater node with an external antenna close to that one and this solved many issues. Also I've added a wire antenna on some modules (similar as in this https://forum.mysensors.org/topic/9947/nrf24l01-si24r1/9 and https://www.instructables.com/id/Enhanced-NRF24L01/) and that solved all issues.
For now at least
I have tried to read up on ACK but it is very confusing. Is there a way I can keep re-sending battery messages until the controller gets them? Domoticz does say ACK is enabled on the battery child.
You can check if you receive a hardware ack by checking the return value from the send() function. It returns true if the hardware received an ack from the receiver. This is only on hardware level though and it could be the software didn't receive it (if it isn't running for example). Or the other way around, you don't receive the ack but it was sent by the receiver.
It could be the motion sensors had the repeater as their parent and they cant find it (or reach it) anymore. Did you try to reset a sensor to see if it will connect to the gateway directly?
Connection problems with NRF24L01 are quite common. This could maybe help https://www.instructables.com/id/Enhanced-NRF24L01/
@njwyborn are you sure the board is not responding? Perhaps the message is never delivered due to connection issues? What type of transceiver are you using?
@kted The chip can work on different frequencies, but the discrete parts and the antenna are tuned for this frequency.
As the frequencies you want to try are quite close, the discrete parts are the same and changing the frequency is a matter of settings in the chip. So a different sketch. And perhaps cut your antenna a bit.
I'm not using a wired connection, but had many connection issues also. It took long time before the gateway was up, MQTT connections dropped.
Then I replaced my router (the one delivered by the cable supplier) and I have no issues anymore. So that could be worth a try.