I'm trying to figure out what has changed in regards to multiplayer on my end over the past month or so. I was able to successfully host a game on my computer (2014 15" MacBook Pro, OS X 10.10.1, 16GB RAM, NVIDIA GeForce 750M) through my Airport Extreme over a period of a month prior. My friend is using Windows, but I do not have the details. Sometime around version 0.11.6/0.11.7, we could no longer play games together -- the game would noticeably stutter as we tried to play, making it almost impossible to do anything.
I'm guessing that it's probably a problem on my end somehow, but I don't have a good way of diagnosing what is going on. Is there any debugging information that I can turn on or look at that could tell me what is going on? I don't know if the issue is that packets are being dropped or just arriving slow.
Are there any tools that I could run on my machine and on my friend's machine to see what's happening?
Was there any changes since 0.11.6 that could've affected multiplayer like this? I do realize that multiplayer over the net isn't something that was meant to work, but it was working for at least a little while for us, so it would be nice if I could somehow get back to that at least

Thanks!