Windows 7 - Download speed is limited, but upload speed is fine

Hi everyone,
At first I noticed a slow down with my ISP (Verizon FIOS) from 15mb/s to 6-7mb/s, but the upload speed is unaffected. So, I called my ISP they told me could be an issue with the Windows that I am using.
Then I called MS regarding the network issue, however they told me that my license has expired is not under warranty for technical support. Here I am asking for some help.

Some of the thing that the ISP done was conducting some test:
Buffer size:261360 bytes
Receive size: 66608 bytes
Their ISP network technician told me that the Receive size was too low and causing problem to the download speed, but the upload speed is still good.

So, anyone who have any suggestions will be greatly appreciated.

are you using a router?
if yes, try bypassing the routing by plugging directly into the modem.

Yes, using the ISP provider's router. We have already reset the modem and router before.

but have you plugged directly into the modem and tested your download speed?

The modem and router is built-in as one unit, but I had just try just plugging into the WAN still same result.

ok, so you are running Norton and they didn't determine that as the culprit so far.
Are you running any bitTorrent software or FTP server software?

Is QoS enabled on the router or NIC?

I don't have Norton, I have Avast anti-virus. I mean the speed was working pretty fine the first 5 months.
No bitTorrent software or server software running.

Not sure what is the QoS on the router.

Ok so working backwards, what changed after that 5 month period? any updates, new software added?

Seems like only after that Adobe keep flashing up I don't recall any slow down for previous softwares. There could be some updates that I didn't realize like whenever I shutdown there is sometimes some updates going on.

So it's prompting you to update adobe?
Have you manually updated your network card driver in the last 5 months?