Poor streaming throughput



I'm not sure if this is a problem with my media server or what, but when streaming movies via the browser on a computer, I seldom, if ever get any warnings about the network not being fast enough to stream a movie. But when I stream to my iPad Pro, I get it a lot. Not all the time, but a lot - and it seems to happen more during action sequences, but I can't be sure.

I have gigabit fiber into the house and a gigabit network. It's wired gigabit to my wireless router in our bedroom. The router is probably 20 feet from our bed/where I watch the tablet. The router is running only at 5GHz so there's no mixed-mode issues, and I routinely see download speeds of 300-400 Mbps from both an Internet speed test and a network read test from both my media server and the Thunderbolt Pegasus RAID attached to it.

When I change the movie quality to 720p on my tablet (from it's native 1080p), things are much better (though there's occasionally a hiccup).

My media server is a 2012 Mac Mini, 2.6GHz i7 with 16GB 1.6GHz DDR3 RAM and an SSD. It's currently running the latest OSX, High Sierra.

I feel like the network is clearly fast enough to support streaming 1080p. So is the computer hardware just not capable of transcoding it? I'm completely at a loss here.