Ok i have found a little bug in my code, connecting to blynk server two times in
void setup ()
Blynk.begin(auth, gsmAccess, gprs, client, pin, apn, user, pass);
// Blynk.connect(); //this connects to blynk, same does Blynk.run in the loop
Second point about heartbeat, i have found the heartbeat which could not be changed in “Arduino\libraries\Blynk\src\Adapters\BlynkArduinoGSM.h” line 18:
#define BLYNK_HEARTBEAT 600 /*original 60*/
Tried 10mins heartbeat now, it works so far, no disconnect message in the app.
Not sure if it is a Blynk-BUG, that definition is not possible in code.
EDIT: i previously forgot to say, i have disabled offline notification in the app.
I have now set the heartbeat to 6hours, but it would great to turn heartbeat completely off, because for the server it would be the same if the command comes from the heartbeat or value send.