Firstly, here is my system:
Draytek Vigor 120 in PPPoE bridge mode -> ALIX 2D13 with PFSense -> Gigabit Switch (unmanaged) -> Intel PRO/1000 CT NIC.
All Wired CAT6.
No other active devices on the network (for the purpose of troubleshooting this issue), and no bandwidth using applications on the PC.
Now, the issue is depicted HERE. Wild fluctuations in streaming speed when trying to watch a video from Youtube, and the downloading even appears to drop out altogether and then resume it's erratic behavior. Some days it seems to be working OK with fairly consistent speeds, but most of the time streaming HD videos is impossible.
Tonight I was getting extremely frustrated with the issue and tried rebooting PFSense, and interestingly enough, when I went back to the same video I noticed that it was downloading at a steady 7000-8000kbps - I thought the reboot had fixed it, but after 1.5 minutes of fast, consistent streaming it suddenly resumed it's old behavior and the video was unwatchable.
So I tried rebooting PFSense again. Same thing happened. About 1.5 minutes of perfect streaming, then back to unusable. I tried two more times to make sure this wasn't some kind of fluke.
So it looks like the problem has something to do with the PFSense router. My knowledge on PFSense (and networking in general) is severely limited. I've none little more than the initial setup wizard. Does anyone know of a reason why this strange issue might be happening, and why it's resolved briefly by cycling the router? Possibly something I've configured wrong in PFSense?