> Andreas, I'm trying to identify which Push Network your application uses, could you list types of variants listed in the application that fails? e.g. GCM, APN..

The application in Aerogear push has one variant, which is APN (iOS).

> You could also try to fetch a debug log so we could get more insight - here is how you can switch wildfly to debug mode for a little while in production and then turn it back while this "defective" push message is being sent:

Thanks, will try that.

> Andreas, do you have a lot of installations in your production env?
I guess the EJB could potentially time out while sending the messages to push networks (depends on your configuration of the wildfly container).

There are many thousand installations in the production env.