After investigation, I confirmed that my Lenovo ThinkPad X200 has connection problem when it is connecting to the N router. It is working fine at G mode.
The workaround would be disabled the N mode for the Intel 5100 AGN wireless card at the moment. My solution is :
sudo nano /etc/modprobe.d/options.conf
And add the following to it.
options iwlagn 11n_disable=1 11n_disable50=1
After investigation, I confirmed that my Lenovo ThinkPad X200 has connection problem when it is connecting to the N router. It is working fine at G mode.
The workaround would be disabled the N mode for the Intel 5100 AGN wireless card at the moment. My solution is :
sudo nano /etc/modprobe. d/options. conf
And add the following to it.
options iwlagn 11n_disable=1 11n_disable50=1
After that, reboot your system.
Please fix this bug, thanks.