cdx304 wrote:
Why do you people judge speed through WIFI will never get max speeds use wired gigabit
I just find the cable keeps getting tangled up behind me as I walk around the house. 
There are 3 steps to actually finding out what's causing the WiFi interference:
1. Install an app like WiFi Analyzer on your phone and check what other WiFi networks are operating in your area and their relative signal strength at your location compared to yours. Then you can consider whether a different channel would do better, keeping in mind that many WiFi routers already hop between channels automatically when they get too much interference on the current channels, and that in the 2.4 GHz band you can only get 3 channels that don't overlap to some extent.
2. Unfortunately none of these WiFi analysis apps show you another important factor: how much traffic is there on these competing WiFi networks? A lightly-used network may not be interfering much at all, while one that's streaming at a high rate continuously may be interfering a lot. You need a different app to check traffic, and you can generally do it only on one channel at a time due to hardware limitations of the WiFi adapter. I use Nirsoft WiFi Channel Monitor running on my Win10 laptop to check channel traffic on my chosen channel. You can see all the packets being sent on that channel on all networks nearby, though of course you can't decode those from other networks.
3. Consider possible sources of non-WiFi interference in that band. For example lots of things interfere with 2.4 GHz, including microwave ovens, smart home devices using a Zigbee network (like Philips Hue bulbs), Logitech wireless mouse/keyboard, analog video transmitters, some cordless phones etc.
