Actually it was my previous Linksys router that experienced the very same symptoms that you described that caused to investigate what was going on and the reason why I ended up with a DIR-826L router.
In MY case, I discovered several things: there are between 8 - 11 other 2.4GHz radios operating in close proximity to my house, the 802.11 channel width is greater than the frequency difference of each channel, which means that only channels 1, 6, 11 are free from interference from each other. (Channels 2, 3, 4, 5, 7, 8, 9, 10 all "bleed" into each other.) I have also noticed that over the last few weeks, 4 of my neighbors now operate on channel 1, 4 are on 6 and 3 are set to channel 11. So no matter what channel I choose, there is "interference". Using speedtest.net I was getting ~3Mbps via wifi. The 2 computers that are wired to the the router would get in excess of 27MBps.
According to specs, the router and the device negotiate down to the slowest speed there is a stable connection. But have you ever noticed how a radio will fade in and out when you are on the edge of the range of the transmitted signal? So either the router and the device are smart enough to renegotiate, which seems to cause loss of syncing when I am streaming, or new interference disrupts the currently "stable" signal. Either way I experienced random, slow, apparently unstable, operation.
Enter the DIR-826L 5GHz radio. Voila! Wifi speeds same as wired. Solid, stable operation while streaming. So nice NOT to see the wheel start whirling during a particularly intense scene!
So that is my experience. I found an article titled "10 Reasons Why Your Wifi Is Slow" to be incredibly helpful. I'm sure you could find such info with Bing, Google, Dogpile, etc.