Push Notification with proxy
<p>I'm stuck with a strange android behavior and I'd appreciate if anyone can suggest me how to proceed.</p>

<p>I’v developed an App with gcm first, now upgraded to fcm, to just send messages and notifications from a server. Everything goes well using this app with mobile connectivity or with wifi on an open network, but the devices stop to receive notifications when they are connected to a wifi behind a proxy. </p>

<p>The proxy is of course configured on the device and they can surf on internet, read email, connect to the machine with the gcm server installed; they just don’t receive notification… and not only for my app but for all apps, like hangouts, whatsapp and gmail… </p>

<p>Probably google play service cannot connect with google server… but what can I do to force it?</p>

<p>I can manage all the network settings, I've removed the firewall, all ports are open. If I connect to the normal gateway everything works, if I connect devices to this transparent proxy, notifications stop to arrive. </p>

<p>I’v read on forums that most users use “Drony” or they root the smartphones, unfortunately these devices are in a production environment and under warranty, I cannot install third-party app or root the devices.</p>

<p>In my app I don’t manage directly proxy configuration, this is a OS configuration, but is it normal that android notifications don’t work behind a proxy?</p>

<p><strong>Update:</strong><br>
       following this topic  <a href="https://stackoverflow.com/a/31832657/2358012">https://stackoverflow.com/a/31832657/2358012</a>
       and dialing <code>*#*#426#*#*</code><br>
       it gives me that using proxy, google play services are disconnected ->             connection failed.
       Probably the TCP connection doesn't pass through the proxy.
       I've set up also a SOCKS server, but in Android, without root, is not possible to configure SOCKS connection, right?</p>