Probably the wrong forum, but anyway... Whilst trying to connect my watch (VA-HR) to a different phone (iPhone -> Android )and getting this error on the Android, I tried to re-connect back to the original iPhone with the same result: "We're having problems talking to the Garmin Connect server. Try again". So I did, several times...
The watch is talking to GCM: I have successfully connected it and gone through the "Which wrist?" phase, but it comes up with a Sync Failed red box.
I have tried all the usual tricks: rebooted watch and phone, stopped/started GCM, toggled Bluetooth. It just won't play ball!
[RESOLVED] Well, sort of - I disabled Bluetooth on the watch, removed the Vivoactive HR from the iPhone's Bluetooth list, re-starte BT on the watch, Selected "Pair Mobile" and hey-presto all working again. Only an hour of my life I'll never get back again.