Does JavaScript client not receive extension response sometime?

[crimsonfantasy]

Our game have a countdown event.
Server send countdown event (using SFSExtension Response) every second,
If total time is 15, server send events subsequently to client every second, like this 15, 14,13....0
Server logs every extension response before sending response.
Every thing are well in log file, but client say that not received one of message something, not frequency.
How do I trace this kind of issue?
Thank you.

[Lapo]

Hello,
Javascript uses websocket, which uses TCP, so packets are guaranteed to be transmitted and delivered in order.

If a client doesn't receive one of those timer events it should also stop to receive anything else after that.
In other words if a client receives timer event 15, 14, 13 and then stops, I would expect no other data is ever received from the server.

Is this what is happening?

Thanks