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Android Devices Unable to Consume REST Service on Wifi

Hello there long time reader of Stack Overflow but first time poster,
I am a bit new to android development but we decided to build a Xamarin.Forms app which consumes our ASP.NET REST service. When running the app on an emulator on my computer, connected via ethernet, I am able to connect to the service. However, when running on a tablet or phone that is connected on our work wifi, the connection just hangs and times out.
Interesting enough, when the device is switched to mobile data it can connect to the endpoints again, and iPhones can connect to the endpoints on mobile data or wifi.
I'm curious what I'm missing here. Please let me know what you think or additional information I should include.

While this thread has been opened for some time, we have found our problem resolved: it was a mixture of our network support changing some settings on our routers (though I can unfortunately not remember what settings) and also our tablets do a system update.
I am not sure which of these factors was the cause of our success now but the issue is done. I just wanted to post this in case anyone else ran into something similar.

Using developer voice commands result in a network timeout error and hangs voice control

Since last Tuesday our project team have had some issues with the google glass device. We are working on an app that is using custom developer voice commands to launch and navigate through contextual voice menus within the app.
Our app has worked fine before, but now all of the sudden, developer commands won't work anymore. We have followed all instructions on how to setup the AndroidManifest.xml correctly for glass, and also how voice menu items should use the strings.xml. What's also interesting to note is that the problem seem to be unrelated to our app in particular. None of the apps we have tested so far with custom voice commands work.
The voice control hanging issue seems to be related to an inability for the device to connect to a remote (google?) server. Whenever we are connected through a wifi network and start our app, any voice menu with custom voice strings seem to hang. After about 30 seconds we see that logcat is printing the following: 824-1002/? I/ProtoRequestDispatcher﹕ Request failed due to network error [message=Read timed out].After the timeout it sometimes tries to connect again to receive the very same error, or it goes back to the "ok, glass" menu. Sometimes (but not always) the voice control hangs without returning or trying to reconnect. Our last resort in this case have been to restart the device.
When we are not connected to any network we receive no timeout and the voice control doesn't hang. Any custom voice commands don't work here however. Pre-built voice commands that are present on the device work offline.
Another note is that some of the in-built voice commands won't work either, such as "Plus One" and "Dismiss Event". Like custom developer commands whenever we try to use these it gets stuck trying to connect to the remote server and timeouts. Without a network connection, these don't work either. A guess is that these also need to be downloaded once.
We have tried a variety of apps with custom voice commands. We have also tried to reset the glass device to factory settings, and created a new google profile. Switching to other wifi networks have so far not helped either.
Is there anyone else that have received this server timeout issue or that have any ideas of a solution to the problem? We're aware that developer commands require a network connection the first time they're used in order to receive a some sort of template to use when decoding it upon speech. We seem to get stuck before this stage though, and are very unsure how to proceed.

LAN calling in android

I want to develop an android application for LAN calling.My app resembles apps like whatsapp, viber etc, so I googled for the same. What I got from different answer is:
Whenever we install whatsapp, the whatsapp server register our number and contact list. The app continuously pings the server and update its status on server.
When we open the app, it gets the data from server, and if a number is found in contact list, it displays the status of the number and other things.
Whenever we message some one, the message goes to server and stays there until delivered successfully.
For my app the two steps are:
Find all the devices which has my app, their IP and mac address.
When devices are found,allow calling between them.
For step 1, I have two options:
As whatsapp, I can have a server. It registers the info of the mobile phone, whenever the app is installed. The app pings the server and shows its status.
I can use my own network device discovery code. This code scans the network and find the devices.
This step is costly, whole network is flooded with the packets. And also it is quite difficult to write network device discovery code.
For step two, I want to implement client-socket programming and simply connect the microphone of one device to the speaker of another phone. I think it is challenging, but it is possible.
Please help me with network discovery code or the server setup. I am quite familiar with android development, but very novice to networking.
Also how calling is done between these devices?
I have searched for the answer and found the following links: Peer-to-peer SIP call with Android SIP Stack?
how to implement voip in android
VOIP on Android libraries or sample code
I also put a question on quora:
https://www.quora.com/How-can-I-develop-an-app-having-feature-like-whatsapp-calling-in-android
But, still I am stuck at the beginning. Please help me with it.

Not a complete answer yet, but here are the things to look for:
Assuming Java is your language, use Multicast Network discovery in Java using multicasting and https://en.wikipedia.org/wiki/IP_multicast
Calling needs more description. Does the call starts immediately (as soon as the peers detect one-another) ? How does one know the identity information - a number or a username etc. ?

Why do i get time out in bluemix sample app?

I have followed the tutorial of bluemix that is called bluelist. See here: http://www.ibm.com/developerworks/library/mo-android-mobiledata-app/#N1021F
I have installed all required libs and i have installed everything in the bluemix side.
I get error IBMBLUEMIX-0554E: timeout expired before connection could be established.
any solutions?

This could be caused by a couple issues.
You could be attempting to access an internal test zone (AKA stage1) without being in the internal network. Make sure there is not stage1 present in your app route.
Your phone/emulator may not be connected to a network properly. Please be sure that your test device is connected to the internet via data service or local connection. You can try running a speed test on that device if in doubt. Some custom created emulators can also have issues of their own. Try using a physical device if possible.
You may be on a network using a proxy server. I have heard of timeout issues when using a proxy. You may need to use a network that does not utilize a proxy.

This issue comes intermittently some times due to network/connectivity issue.Also you need to Verify that your applicationId, applicationSecret, and applicationRoute are correct.You can go to the Overview of your Mobile Cloud Service application on ACE to find your applicationId and Route. The applicationSecret is on the MAS portion of the ACE UI for your application.
Similar issue was reported already:
https://developer.ibm.com/answers/questions/26821/getting-time-out-error-while-conencting-to-mobile-cloud-bluemix-application.html

How to send notification from one android device to another android device in same wifi network

I want to send notification from one android device (android tv without bluetooth, telephony) to another android device (phone/tablet). Both are on same wifi network. Through the notification, I want to launch an app or open a page in phone/tablet browser.
I went through GCM messaging and also saw some options where we can have a kind of http server on the phone running but could not understand implementation.
Can someone help with idea and if possible, some piece of code as well.
As I need it for demo, so even any hack solution is fine for me :-)
Thanks for any help or reading.

Your best bet as a hacky solution is to do simple Socket connection between two devices. Since they are on same Wifi, it will be simpler and won't have any firewall restrictions.
Avoid GCM, it requires setting up a GCM Server and then complex registration. It also makes your solution dependent upon Internet connectivity & Google ofcourse.
See an example here:
http://android-er.blogspot.in/2014/02/android-sercerclient-example-client.html
Basically one device such as TV can be a socket listener. The phone/tablet can connect to that socket and then you can initiate a notification on either device based on your requirements and data exchange.