I´m facing the same issues on a Quest 3, since maybe a week or so.
Streaming has become impossible.
DeoVR 15.6.3755
Quest 2.4.1034
I have a 1 Gbit/s connection.
Speedtest on desktop via ethernet shows consistent 1,13 Gbit/s download and on Quest 3 over Wifi 6 around 300 Mbit/s.
Tried checking if the issue occurs on desktop DeoVR via Airlink, but H265 videos aren´t playing at all. Just an eternal loading wheel.
Playing videos in the browser is very fast, no buffering. So it shouldn´t be related to network issues, like providers throtteling speed to certain CDNs.