Figured I”d at least post this somewhere, since Sony made a pathetic move today (April Fools, yeah right) that affects a large number of PS3 owners; the removal of OtherOS. The 3.21 update apparently does nothing but remove a feature for “security concerns.” I didn”t even want to install it on my PS3 Slim, so I went and adjusted my server to bypass the update for myself and others.

Basically, this will allow you to use the PSN and play your games online while still having an older PS3 firmware version installed, such as 3.15.

If, eventually, a disc game comes out that requires 3.21, you will be forced to upgrade to play that game; there”s nothing you can do about that yet. But in the meantime…

You can go to customize your network settings from XMB, and get to the part about DNS nameservers. Select custom, and enter the following IP as your Primary DNS:
67.202.81.137

And there you go, PSN works.