WyomingKnott said:
When you did the test, was the laptop also running the apps that cause the problem on the desktop?
No. Unfortunately, the apps that cause the problem on my desktop surpass the minimum system requirements of my laptop, so testing the exact apps isn't possible. I tried to watch some live videos on my laptop to lure out the problem, but it didn't show itself. However, I couldn't replicate the problem purely by watching live videos on my desktop either (problem machine). I was able to get symptoms by playing DOTA 2 for about 30 min though. On the other hand, I was playing the same game last night and I started having the issue, but when I quit the game and tried to watch videos afterwards the problem persisted until I turned the computer off and went to sleep.
When I go on Skype, my ping goes from steady ~50 to jumping to 1k every 20ish packets. It's enough to be able to hear the problem on Skype without looking at the ping monitor. After the call is over, it goes back to normal.
Another noteworthy feature of the problem is that it usually gets worse over a continuous gaming session. It'll start off fine for the first 15 min, then get steadily worse until 30-60 min when it becomes unplayable. Likewise with Skype. Call quality worsens as the call goes on.
UPDATE: I put the desktop on a wired connection (didn't do so before because it's kind of a pain to move), and that seems to have fixed the issue.