Well..I have the same issue....and I have A1 with firmware 1.11NA . I did just go through the "problem" with losing connectivity altogether, because "advanced DNS" was enabled....read other posts on that topic.
Now I am getting the slow-down instead. Uplink speeds down from 2kbits to 200kbits (yes, bits not bytes, and I understand the difference.)
My biggest problem is that it isn't just across to the modem (and out the internet) it is through the DIR-825 router to my NAS as well! Files which took 5 minutes are taking an hour...eek!
So, the trick to see if the router was hosed was a simple unplug-power then re-poweer the router. If that repairs the speed...then it is obviously a problem with the buggy 1.11NA firmware. (sorry DLINK, but hey..)
Now, about that beta firmware, I have read too many uncertain stories as of the time of this post to try it myself. But please, anyone (not a vendor) who feels they have sufficient evidence that it repairs the A-series firmware problems, please chime in!
For now,