I've been working on getting my router set up correctly and have been running into a pretty major issue: when my roommate is streaming Netflix to his laptop or smart TV, it pretty much kills the WiFi. My Internet speeds drop right off, gaming becomes impossible, Youtube etc play at low quality and take a while to buffer. Web sites go from pretty much instant to taking several seconds to load, if at all - I've gotten a few "408 Request timeout" errors. I've tried changing channels and disabling QoS to no avail.
I'm pretty sure the problem is that the router's WiFi throughput is being saturated, as accessing the router configuration page is just as slow, and even pinging my router yields results ranging wildly from 70 ms to almost a full second. If I watch the ping at the moment my roommate shuts off Netflix, it'll immediately drop to a consistent 1-2 ms.