never had a problem before but since the new software when i watch a youtube video about ten seconds into it it reboots the router and calling on skype about the 3rd ring it disconects router from internet ,i installed the update twice and second time didnt bring my backup across didnt make a difference and i also installed new firmware into router the router is flawless with psp's mac book , sony mylo so im stumped thanks for looking guys hoping for maybe a answer

Might be worth raising a bug report in bugzilla. There is an existing 11n/Airport Extreme bug (bug #1459) which may suggests upgrading the Apple firmware, but since you've already done this it may require further investigation.