I pretty much just want to ask this exact question: askubuntu forum only for elementary (freya). I cant figure out how to do it with the normal network settings.
As the solution in the askubuntu forum proposed, I was searching for an option called Band. However I cant find any options in the Network settings, that adjust the frequency, as I wish. Or I just cant recognize it as one.
Run lshw -class network. Look at the logical name for your wireless card. Let that be denoted <wlan>. CD into a relevant directory, store your current wireless config: iwconfig <wlan> > current_wireless_config to restore settings later if need be.
Post the output to iwlist <wlan> channel here. You may wish to follow the advice in this answer: https://askubuntu.com/a/55748 or you may download linSSID from the app center and find a good open channel and frequency and set it as follows.
Turn your wifi off, then run:
sudo iwconfig <wlan> mode Managed
sudo iwconfig <wlan> freq <desired-freq>
sudo iwconfig <wlan> channel <desired-channel>
Make sure this is in agreement with your output from iwlist <wlan> scan or iwlist <wlan> channel and the frequency matches the corresponding channel. Reboot computer.
WARNING: According to man iwconfig under "freq/channel":
When using Managed mode, most often the Access Point dictates the channel and the driver may refuse the setting of the frequency.
As per your discussion on askubuntu, Managed mode may be the best option you have. So try just that without changing the frequency or channel parameters and see how it goes.
Other parameters of your wireless interface may also be the culprit for your connectivity issues. To be sure, post the output to iwconfig <wlan> in your question.
