I have a Rosewill RNX-n300 PCI wireless card, and since installing 12.04 the connection intermittently stops receiving data. The problem seems to be worse when downloading files, whether from the web, Update Manager, or from the Software Center.
The network manager never shows loss of connection, and disconnecting then reconnecting wireless solves the issue. Disabling
-n speed in terminal improved performance a bit.
I have also disabled power management for the device with (I think)
iwconfig, in addition to disabling the
-n speed setting. I have also tried disabling IPV6.