can you check on the nodes for maplestory global, it seems to always prefer JP nodes when connecting to NA server, Specifically Reboot server. Im from PH if that helps
I think you should check your ISP first. When I checked RTT information recorded in Mudfish, it seems RTT stddev values to most of the mudfish nodes are quite unstable. It means your ISP has a network issue. For details please check http://ko.loxch.com/userrtt/?uid=147022 link.