This is currently defined as a connection delivering at least 10 Mbps download speed and 1 Mbps upload speed (along with other defined quality parameters).
Mae hwn yn gysylltiad sy’n darparu cyflymder llwytho i lawr o 10 Mb yr eiliad o leiaf ar hyn o bryd (ynghyd â pharamedrau ansawdd eraill sydd wedi’u diffinio).