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Why TRESTRequest Execute fail with Timeout Exception on android device?

I have build a firemonkey app to runs on android device but i have some issues with the Execute procedure of TRESTRequest Class sometimes randomnly fails with java.net.SocketTimeoutException.
I've noticed that when I have the wifi enabled the RESTRequest1.Execute is always working correctly but
on the other hand when i enable the Internet Data on the phone, i often get java.net.SocketTimeoutException.
Why is there a difference between Wifi and Internet Data connection?
I tried with ExecuteAsync fuction but i had the same result.
procedure TForm1.Button1Click(Sender: TObject);
begin
RESTResponseDataSetAdapter1.Active := false;
Label1.Visible := false;
Application.ProcessMessages;
RESTRequest1.Resource := 'customer';
try
RESTRequest1.Execute; // java.net.SocketTimeoutException
except
Showmessage('FAIL');
end;
RESTResponseDataSetAdapter1.Active := true;
Label1.Visible := true;
end;

Android USB serial port used from shared library... How?

Am I developing an Android app (in Embarcadero Delphi 10.3) that will use the HamLib library for controlling radios, etc. I've compiled the library (libhamlib.so) with the NDK, and works. I can use the library from the application created with Delphi, but only if using the network connection. (the library connects to another maching, running a server to control the radio)
The goal, however, is to control the radio directly from the Android app with an USB to serial adapter connected to the Android device.
The problem is permissions. I've looked with an rooted phone that /dev/ttyUSB0 is created when the USB serial adapter is inserted. But the permissions on the device is crw------- and owned by root. So the application does not have permission to use the device.
I've tried setting permissions in AndroidManifest.xml and also added Intents (so my app gets called when inserting the USB adapter)
I have also played with the UsbManager and it says the app has permissions. The UsbManager reports the device as /dev/bus/usb/001/001 though, so something is not right. If i tell the library to use /dev/bus/usb/001/001 it fails aswell. And the /dev/bus/usb/001/001 is not the same major minor character device as /dev/ttyUSB0
Anyone out there with experience with Android and serial ports, and of course using the serial port from a shared library?

You could try using usb-serial-for-android library, compile it into a .jar file and add this to your Delphi project.

I use the Comport for Android USB Serial library from Winsoft, and as you can see from this page https://www.winsoft.sk/acpusbser.htm, it has build in functions to obtain permission from the user to use the comport. I'm pasting is some code from 1 of my projects to give you an idea of how Winsoft library requires this to be handled.
procedure TfrmLiveMain.RefreshDevices;
var
i: Integer;
IDString: String;
Device: JUsbDevice;
begin
UsbDevices := UsbSerial.UsbDevices;
if UsbDevices = nil then
EXIT;
if Length(UsbDevices) = 0 then
begin
Sound(50);
Vibrate(25);
FToast.MakeToast('No USB serial devices were found!');
EXIT;
end;
for i := 0 to 1 {Length(UsbDevices)} - 1 do
begin
Device := UsbDevices[i];
if TJBuild_VERSION.JavaClass.SDK_INT >= 21 then
IDString := JStringToString(Device.getManufacturerName) + ' ' +
JStringToString(Device.getProductName)
else
IDString := JStringToString(Device.getDeviceName);
end;
if not UsbSerial.IsSupported(Device) then
raise Exception.Create(IDString + ' is not a supported device!');
// give them 2 chances to grant permission
if not UsbSerial.HasPermission(Device) then
begin
UsbSerial.RequestPermission(Device);
if not UsbSerial.HasPermission(Device) then
begin
PermTimer.Enabled := True; // begin permission loop ->
EXIT;
end;
end;
procedure TfrmLiveMain.PermTimerTimer(Sender: TObject);
var
Device: JUsbDevice;
begin
PermTimer.Enabled := False;
Device := UsbDevices[0];
if UsbSerial.HasPermission(Device) then
RefreshDevices; // and try open ->
end;
Now of course, I can't say if this is what you need for the Hamlib library, so this is an extended comment, and not really an answer.

IdIcmpclient.ping() under Android returns Socket error #1 - Delphi Rio 10.3

Thanks to the help of many Stackoverflow contributors, I have successfully completed my Windows VCL project to, ping a number of IP Addresses, add them to an SQLtable, sort them by ping time and automatically set the IpV4 DNS settings to the fastest 2 addresses. This works perfectly under Windows.
I am now trying to create a similar application running under Android. I am using idIcmpclient to ping the addreses and pick up the IdICMPClient1.ReplyStatus.MsRoundTripTime. The code compiles and installs on my Android test device(s). However when run under Android, I receive a Socket #1 error. The testing code is below.
procedure TForm1.Button1Click(Sender: TObject);
var
ipAddr: string;
begin
ipAddr := '188.132.234.170';
IdIcmpClient1.ReceiveTimeout := 200;
IdIcmpClient1.Host := ipAddr;
IdIcmpClient1.ping();
if IdIcmpClient1.ReplyStatus.ReplyStatusType = rsEcho then
begin
Memo1.Lines.Add(IntToStr(IdIcmpClient1.ReplyStatus.MsRoundTripTime));
Memo1.Lines.Add(IdIcmpClient1.ReplyStatus.Msg)
end
else if IdIcmpClient1.ReplyStatus.ReplyStatusType = rsTimeout then
begin
// have a timeout, link is down
end
else
begin
// do something else
end;
end;
I have looked to see if there are peculiarities with IdIcmpclient and other OS's and have found out that it does not work with iOS , something to do with Raw Sockets.
I am assuming that maybe the same case applies to Android, which leaves me with a bit of a problem and possibly an untimely end to my new Android project.
If IdIcmpClient.Ping does not work under Android, is there an alternative method to Ping addresses and get the return times.
Any help much appreciated

SIGBUS when trying to call recv on socket after server crash (Android 6.0.1)

I am currently doing some app stability testing and I am running in to an issue when calling the following method;
vector<char> buffer( 256 );
received = recv( fd, buffer.data(), buffer.size(), MSG_NOSIGNAL );
In this case fd is a TCP socket. When the above code is called and simultaneously the server side of the socket goes down in one way or another I get the following signal;
SIGBUS (signal SIGBUS: illegal alignment)
It only seems to happen on Android 6.0.1 and I can't seem to 'ignore' the SIGBUS using
signal(SIGBUS, SIG_IGN)
Has anyone else run in to this problem and what would be the best approach to solve this?

Oke, I have found out the issue. It has NOTHING to do with the call to recv. The signal occurs when and std::exception is being throws on Android 6.0.1. Even though it blames the recv call. This seemed to be caused by the c++_shared STL version I am using. The solution was to switch to gnustl_static or gnustl_shared.

How can I do connection with Bluetooth Printer with Android?

I want to connect with Android to a bluetooth printer with Delphi, using the technique described in the Bluetooth Paired Devices Browser example by David I.
My printer is the Panda BIXOLON SPP-R200II:
I get the Error:
"java.io.IOException: read failed, socket might closed or timeout, read ret: -1"
by sock.connect;
Here is my Code:
procedure TForm1.ListView1ItemClick(const Sender: TObject;
const AItem: TListViewItem);
begin
ShowMessage('You selected: '+Aitem.Text);
// depending on the bluetooth device selected - do something with it
targetMACAddress:=Aitem.Detail;
if trim(targetMACAddress)='' then exit;
Adapter:=TJBluetoothAdapter.JavaClass.getDefaultAdapter;
remoteDevice:=Adapter.getRemoteDevice(stringtojstring(targetMACAddress));
sock:=remoteDevice.createRfcommSocketToServiceRecord(UID);
try
sock.connect;
except
on E : Exception do
ShowMessage(E.Message);
end;
if not sock.isConnected then
begin
ShowMessage('Failed to connect to Try again...');
exit;
end;
listview1.Visible:=false; // hide the chooser
label1.Visible:=false; // hide the chooser
reload.Visible:=false; // hide the chooser
end;

All communication made with the Bluetooth device must be carried out through Threads.
I transcribed a project in Android Studio for Delphi, using threads, and everything worked.
Do not use Timer, use the TThread object.