Force transcoding of 4k Videos to 1080p

[TheDreadPirate]

On the client

Click on the user icon > Playback

Try fiddling with the "Home network quality" and "Maximum Allowed Video Transcoding Resolution". You can also try to specify a User specific bit rate limit or a global bit rate limit

Settings > Dashboard > Users > Click the User > Internet streaming bitrate limit (Mbps) (About halfway down)
Settings > Dashboard > Playback > Streaming (tab at the top)

The phone should be negotiating this, but hopefully one of these options will workaround the issue until it is fixed.