520 plus er absolutt ikke for gammel.
Jeg bruker den eldre 520, som fortsatt fungerer glitrende.
Jeg opplevde noe av det samme - fant da ut at det beste faktisk var at Edgen ikke allerede var koblet til telefonen.
Se også her (
Garmin support center):
Step 6: Make sure your device is not already paired directly to your phone's Bluetooth
If you accidentally paired your device to your phone's Bluetooth settings and not through the app, there is a chance the Garmin Connect app will not find the device. You need to go to the Bluetooth settings on your phone and un-pair the device. Consult with your phone manufacturer or carrier if there is a question on how to do this.