ReadyNAS was great, slowed greatly

Hello,

I am not really "new", but not very technical when it comes to NAS units.

Here's what I know:

With my existing network, not one piece has changed in over a year.....I used to get phenominal speed (at least to my standards) downloading to my NAS unit from my MacBook Pro.  I do not know the exact speed, but what I do know now is that the speed over the last couple of months has droped to nearly exactly 1/10th the speed I was getting.  

What will happen is I will have a download going, speed will spike for 2 maybe 3 seconds then will drop and hover right around 700kb/sec - 1.2mb/sec.....when it used to hit 7000kb-10000kb no problem and for hours on end.

Again, in this scenario I don't know that specifics really matter, what my real question is, does anybody know what would cause this without any previous issue and nothing changing on the network.  Its not like it stopped working, it just got "tired seemingly"  something is off for sure.

I have destroyed the volume and recreated even, same result.  I know my network is much faster with other tests i've done.  Everything on the network is fine except the NAS unit, and it even is fine....just very slow to respond and write speeds seem to be the issue...they have just slowed to 1/10th what they used to be.

Thank You,

Justin