If not for this article – What is Interference Robustness? – I would have never known what is it.
When should I use it?
It really depends on the situation. Some users will experience WLAN issues based on the specific products they have in their home in this case use Interference Robustness. Others will face WLAN issues because they either live or work in a highly populated area such as an apartment building or office building. This would be an ideal time to use Interference Robustness. Basically, whenever you face WLAN interference that is caused by outside variables, Interference Robustness will help.
If it cuts down on interference, shouldn’t I leave it on all the time?
No. This is very important to understand. Using Interference Robustness will essentially slow down your wireless connection. As discussed above, if you’re looking for speed, you send a high frequency of large packets. If you’re looking to battle interference you send smaller packets at a lower frequency. So your connection will be slow but strong.
Read the article in full.