This just started happening recently. WIFI basically goes to a crawl/slow speed for no reason.
I basically narrowed this down to the router.
Done speed tests from the modem and its at 200mbps speeds. (its not the internet connection through the modem)
Used mutiple devices to run speed tests (its not effecting one device, its effecting all devices)
Connected directly to the router via cable and the speed is 200mbps (limits the problem to wifi)
This has been happening just after noon for the past 2 days, however when I wake up and check in the morning, things are back to normal and great and stay steady through the morning (its just me on the network). Testing wifi speeds are ~17mbps and at best 30mbps
Solutions:
I have reset the internet connections on my laptop and it did not change.
I have also reset the router to factory defaults on that firmware and still the same result.
It is possible that your neighbors have the same wifi channel you do. Try changing the wifi channel.
You google "how to pick the best wifi channel for my router" and you'll find several web pages that will let you map out your local wifi channel usage. Run these at a time when you are having issues (probably neighbors kids waking up and starting their gaming :).
I actually ran through all of the channels, nothing worked faster than channel 120. I get a around 480 mbps down, on a CenturyLink 1Gbps (940Mbps) fiber connection; using a Intel 9260 chip, connected at 1.7Gbps to the router.
