Why fprintf or fflush not throw a error when UNC is inactive

i guys,

I'm seeing that fprintf or fflush not throw a error when a UNC path( \\computer-name\shared\logs\seq.txt ) is inactive. 

I started my app and i'm unplugging network cable.

fprintf or fflush not return error when UNC path is inactive.

Somebody knows something about this? 

// app sample
std::string m_seqNumsFileName("\\\\comp-1\\storage\\logs\\seq.txt");
FILE* m_seqNumsFile = NULL;

errno_t i = 0;
  
i = fopen_s( &m_seqNumsFile, m_seqNumsFileName.c_str(), "r+" );
if ( !m_seqNumsFile ) i = fopen_s( &m_seqNumsFile, m_seqNumsFileName.c_str(), "w+" );

int iSender = 0, iTarget = 0;

for( int a = 0; a < 100; a++ )
{
	  rewind( m_seqNumsFile );
	  fprintf( m_seqNumsFile, "%10.10d : %10.10d",
			   iSender++, iTarget++ );
	  if( iSender > 10 ) // Unplugging network cable
	  if ( ferror( m_seqNumsFile ) ) 
		  throw std::exception( "Unable to write to file " );
	  if ( fflush( m_seqNumsFile ) ) 
		  throw std::exception( "Unable to flush file " );
  }