On 4/4/11 a number of us experienced problems logging in to the PSN servers. Infiniti found some helpful information posted below:
Yeah, I was having that problem yesterday. Couldn't get logged in to the PSN servers. Tried rebooting both the PS3 and my router... no luck. I had an internet connection as I could use the browser to get on the web, just not the servers. I still don't know exactly why it was happening, but I searched for a fix at the PSN forums and this is what I found....
Needed to go into my network settings..
Setting Methos...... Custom
For me I used wired connection
For operation mode of the network device... Auto-detect
IP address ... Automatic
DHCP host name... Do not set
This is what I had to change...
DNS setting..... Manual
Primary DNS......... 8 8 8 8
Secondary DNS..... 8 8 4 4
MTU ... Automatic
Proxy server... Do not use
UPnP ..... enable
Again I don't really know why I had to do this as I have been using the same setting for the last 3 1/2 years...