Did you go back into your PS3's settings and correct the info in there (putting in the IP address you put in the router, adding router IP/ Subnet mask/ DNS server)? If not do this and give it another try. if it still doesn't work after that the Sony tech support should be able to find what one last detail is missing.
Meantime, you can grab the update via your PC and update that way- i have the .zip file of it in our PS3 Downloads section.