[ubuntu] wifi not working

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http://ubuntuforums.org – Hi, I have a Dell Inspiron n7110. I run unbuntu version Ubuntu 12.04 My wifi is some places just dose not work it will work for like 2 minutes then stop. so I enter "sudo rmmod iwlwifi" and then "sudo modprobe iwlwifi" and that would solve my problem for like 2-10 minutes. Then I found that if I entered "sudo rmmod iwlwifi" and then "udo modprobe iwlwifi 11n_disable=1" it solved my problem tell next time I signed on. The place I found this information said how to make this permanent but I could not figure out the instructions can anyone tell me how (Hardware)