Having the same issue in Precise with Intel Corporation Centrino Advanced-N 6205 (rev 34).
B/G are fine. N works really well at first then plummets in speed to less than 1 Mb/s and becomes unusable. Rebooting the router causes it to work again (really fast), then it plummets again.
Using the iwlwifi 11n_disable=1 is the only way I can work wirelessly with my router.
Having the same issue in Precise with Intel Corporation Centrino Advanced-N 6205 (rev 34).
B/G are fine. N works really well at first then plummets in speed to less than 1 Mb/s and becomes unusable. Rebooting the router causes it to work again (really fast), then it plummets again.
Using the iwlwifi 11n_disable=1 is the only way I can work wirelessly with my router.