Hi David, the app seems to be working and you’ve enabled the notify properties properly…

Your app looks way different than mine (I’m using Android). Can you see the service “91bad492-b950-4226-aa2b-4ede9fa42f59”? And then, open it to see the characteristics?

When you pressed those notifications icons did, you’ve enabled the notify property:

When you enable the notify property in the app, do you have your Arduino IDE serial monitor open? What does it print? Can you see valid values of the DHT sensor?

This is what I am getting in the Serial monitor. There seems to be a callback error.
 
st:0x10 (RTCWDT_RTC_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
configsip: 0, SPIWP:0xee
clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
mode:DIO, clock div:1
load:0x3fff0018,len:4
load:0x3fff001c,len:812
load:0x40078000,len:0
load:0x40078000,len:11572
entry 0x40078a5c
Waiting a client connection to notify…
E (48824) BT: Call back not found for application conn_id=3
Temperature Celsius: 17.00 *C – Humidity: 65.00 %
Temperature Celsius: 17.00 *C – Humidity: 65.00 %

And now I have successfully compiled and uploaded to the client device, this is what I see in the Serial monitor for the client. I see DHT Reading on the display but no data:
Starting Arduino BLE Client application…
Device found. Connecting!
– Connected to server
– Found our characteristics
We are now connected to the BLE Server.
E (21094) BT: bta_gattc_conn_cback() – cif=3 connected=0 conn_id=3 reason=0x0008
E (21094) BT: bta_gattc_conn_cback() – cif=4 connected=0 conn_id=4 reason=0x0008
 

well that’s odd. After rebooting both boards, seems to be working correctly now with temp and humidity showing.
 on the display

That is definitely very odd and I don’t have a good answer for you, because I haven’t encountered that error myself. Did it keep working afterwards?

Yes it did thanks.