In the last few days, Plex started slowing my wifi network radically. Measuring against fast.com from a smartphone, I reproducibly get 10 Mbps when I am not playing a movie and 500-600 kbps Mbps when I am. Most movies to a standstill.
Nothing has changed in the wireless configuration.
Also, YouTube from the same device displays with no slow-down.
I understand that excessive load can slow a wifi network, but other uses of the network, including media-heavy ones, do not cause problems.
How can I go about solving this?