I have recently acquired an old first gen AirPort Express and wanted to use it solely for airplaying over to my old and amp. I tested configuring with it's own network and works fine. The problem is, when I ask it to join my house's network, which is not an "Apple network" and is composed of a few routers extending it. The AirPort still shows on my preferences, is detected by the AirPort Utility but doesn't seem to be reached displaying "Error -6753". I am figuring there is some port configuration I am ought do (?). I don't remember configuring internal firewall in any of my routers (except for the one hooked to the modem), but maybe this is a known issue? Some more details on my equipment: I have the ISP's modem, connected to a cheap Huawei wireless router, which has a firewall configured to keep outbound traffic away. My house has an elongated shape, so midway through the rooms there is another Asus (RT-N10+) wireless router, configured to extend the Huawei's network (configured simply as bridge, no firewall, mac filter whatsoever). The AirPort Express would be in the lower floor, still, closer to the Huawei router (thus what I believe it would connect to). The network itself is SSID broadcasted, WAP/WPA2 Personal Encripted. I will be trying to AirPlay from iPads, iPhones and a MacBook Pro over the house, which will be connected either to the Huawei or Asus router.