What do you mean by sound notification? Is the app in background or foreground? Also, share your device information.
I’m talking about background apps. I did a chat connected with Onesignal. When the other mobile phone sends me a message, I receive the acoustic notification of receipt of the message with a few minutes delay. What can I do ? happens to you too?
There are couple of reasons for delayed delivery of notifications. One of them which I think is the most relevant is:
Remote images and icons, adding an image to your notification could cause the notification to be delayed as it has to wait to download the full image(s) first. Try omitting your image(s) temporarily to rule this factor out.
From OneSignal docs
I don’t know if this can be the problem. The message arrives late even if I don’t send images. Do you have any other ideas? are there other clouds for sending push notifications?