Same here problem here, except that I'm on PC.

Up until March 14th I'd gotten only one or two rare 90k and very little lag. From friday until now, I'm getting 5-20 secs lag and consistent 90k's. Even low level dungeons are nearly impossible like this.

I'm on wired connection, I didn't change anything in my router's settings recently, I checked the network usage on multiple occasions and I tried restarting my hardware. Nothing worked.