OpenVPN TAP I/O operations blocks forever

Question

Following code hangs forever when GetOverlappedResult gets called, I have not much experience in windows async IO operations, I implemented it as per my understanding. I have used it to access virtual network interface (by openvpn - TAP/TUN interface whose kernel driver is installed properly).

I found the place where it hangs, but I don't know the reason why it hangs ?

nread = 0;
memset(data_buffer, '\0', nread);
OVERLAPPED overlapped_read;
memset(&overlapped_read, 0, sizeof(overlapped_read));
overlapped_read.Offset = 0;
overlapped_read.hEvent = CreateEvent(NULL, FALSE, FALSE, NULL);

if ( ReadFile(fd, data_buffer, len, &nread, &overlapped_read) == false ) {
    if (GetLastError() != ERROR_IO_PENDING) {
        std::cerr << "ReadFile failed : " << GetLastError() << std::endl;
        return false;
    }
    else {
        DWORD dwRes = WaitForSingleObject(overlapped_read.hEvent, INFINITE);
        if(dwRes == WAIT_OBJECT_0) {
            if (!GetOverlappedResult(fd, &overlapped_read, &nread, FALSE)) {
                std::cout << "GetOverlappedResult failed : ErrorCode = "
                          << GetLastError() << std::endl;
                CloseHandle(overlapped_read.hEvent);    
                return false;
            }
            else {
                std:cout << "Read successfull." << std::endl;
            }
        }    
        else {    
            std::cout << "WaitForSingleObject failed : ErrorCode = "
                      << GetLastError() << std::endl;
            CloseHandle(overlapped_read.hEvent);    
            return false;    
        }
    }
    std::cout << "bytes read = " << nread << std::endl;    
    CloseHandle(overlapped_read.hEvent);    
    return TRUE;
}

Above code executed in an Infinite while loop inside a thread created using CreateThread API.

Do I have implemented async operation correctly ?

What could be the possible cases when GetOverlappedResult gets hangs ?

PS: Few ReadFile calls were successfull, it can read ethernet frame successfully, but hangs after approx. 15-20 calls.