I have been having intermittant problems with Internet access for the past week. The symptoms are VERY large latency: a ping to a robust web address results in a delay of 200 to 2000 mS, more frequestly around the 1000. A ping test from the router is normal (about 20-30mS in this case).

Since we only have around 20 devices connected I waited for the issue to arise again and went to Diagnostics\Dataflow monitor and disabled client devices one at a time and waited for the constant ping I had running to recover. I found the culprit, got the mac address and looking it up found it was an Apple Inc device. In fact it was a iPhone 4S running iOS5.

Anybody else come across this yet or have any idea why this phone is annoying the 2820 so much? iCloud springs to mind asa possible culprit but what could it be doing? The data troughput is not so high that it made the troublesome device stick out. There were no more that 200 sessions and out Internet connection is "upto" 20 Mb/s.
Any ideas?

iCloud it was. I finally got a chance to sit down with the phone and test various functions while pinging a solid web site watching the response times. When the phone was told to sync to iCloud the problem started approximately 10-15 seconds later. When the sync was cancelled the problem cleared within a second ot two. Did this three times with same results.

The user was including email in the sync which was a little mad as he has Exchange setup (2.4GB) on the phone. He also has another provider which is the one which he really wanted to sync. He had something like 13GB intotal to sync.

I am thinking that perhaps the router was checking the data coming from the phone but spending way too long doing it leaving it short of processing time to work on other traffic?