When Stamina is ON link will break when the phone is in standby ....
I bought mine from Amazon.de.
I wash it every day , even with alcohool for germ killing purposes ( work as a doctor )
Everithing fine until I broke my simcardreader . Sent to Sony Romania wich is my worst nightmare , return with a nasty squeeek...
On 4.4.2 is even beter . pairing is faster , signal is stronger , disconect at longer distance 3m ==> 5m .
Succesfull pairing with xperia z1c ... D5503 ... android 4.3 stok .
First you must pair in bluetooth menu , after that g-shock app will recognize the watch . Is a little workaround , but is working !!!