Since the alleged maintenance at midnight 29/06/12, I have been experiencing severe latency and speed issues. I am using the command prompt to test latency between servers and all of them are exceeding and average of 750ms latency. Occasionaly the ping does not return and times out. I use Dropbox too and when syncing data from the server I was reduced to 5kb/s download speed which fluctuates between <1-10kb/s and is down from 500-800kb/s. Problem was first identified when using an Xbox 360. The ingame connection symbol began flashing and serious lag issues started developing. Lag lasted for about 15 seconds with a 2 second break before continuing to lag. Upon analyzing the problem and running a ping test, i discovered the latency. After tinkering with settings using an internet browser, resetting the broadband username and password seemed to reset the problem and latency dropped to an average of 30ms and normal internet speed was resumed. Upon cancelling the ping test the issue arose again almost immediately. I reset again and it continued to exhibit the same behaviour when cancelling the ping test. I have no idea what on earth is going on but I would like to use my internet without having to run a ping test all the time.
As a side note, the event log shows a port forwarding request being given for port 55650 for a device that has the same mac address as the pc I am currently using but a different IP that has been assigned by the router. It happens on router startup every single time after a few mins and doesn't apply this to any other device.