You are reading your download speed in kilobytes but your modem is rated in kilobits.
It's all bits & bytes to me and not to be confused with the connection speed between your computer & your modem. I found this for your reading pleasure
There is often confusion about bandwidth due to the difference between kilobytes and kilobits. Bits are used to talk about data transfer rates (1 kilobit = 1000 bits), while bytes are used to talk about storage size calculations (1 kilobyte = 1024 bytes). There are 8 bits in a byte. So a 28.8 Kbps (kilobits per second) modem can actually only handle a maximum of 3.6 KB/s (kilobytes per second) of data, including the connection to the ISP, the data holding the TCP/IP packets together, and other essential information. Given all these facts together, your download speeds will often be slower than the "potential" advertised.
