Can I see my pool Temperature on iPhone App?

I installed IBS-M2 and connected it to Wifi. I am able to see the home temperature using the app on my iPhone.
I installed the IBS-P02R pool thermometer and connected it to its monitor.
However, I can’t connect the IBS-P02R pool thermometer to IBS-M2.
On the Inkbird app on the iPhone, I added the IBS-P02R as a sub-device of IBS-M2.
The App shows that the Thermometer is offline. Why? How do I fix it?
Please help.

Just to confirm, when the IBS-P02R-O is connected to the IBS-M2 for the first time, will the INKBIRD APP display the reading of the IB-P02R-O? Now it is the INKBIRD APP that shows the IBS-M2 online, but the IBS-P02R-O offline?
If the IBS-P02R-O is placed next to the IBS-M2, will it connect?
If not, please delete the connection for IBS-P02R-O in INKBIRD APP - IBS-M2 and add it again, will it work?