Hi,
Recently, at night (8pm GMT+8 and beyond), my ping has been really bad for my normal connection (Auto Connection → US West) and especially when I’m grinding. I usually play at 150-170 in the afternoons, but then when it get s to night it jumps up to 200 and with connstant packet losses and ping spikes as well. How can I tell whether this is because of mudfish or my ISP?
Please try to test your network status from your desktop to 52.40.100.23 (Maplestory - North America) using How to use WinMTR link.
I think you need to do two tests; one without mudfish and another with mudfish connected.
I think this result shows you where this issue is from.
Thank you for your quick response. I’ve done two 1 min tests here. I’m not too sure how to read it so I’d be thankful if I could get some advice here.
With mudfish
Without Mudfish
Thank you for these results. 
When I checked it with Mudfish, I can’t see any packet loss in the routing pathes. So it looks good to me.
However when I checked your result without Mudfish, I can see your most of packet loss is happening at Hop 2 (100.81.0.3). This IP 100.81.0.3 is IPv4 shared address space (for details, you can see IPv4 shared address space - Wikipedia). This means that it’s your ISP level.
So in my opinion, it looks like your ISP has some problems with the packet loss.
