I have a Stream Bar Pro connected to my TV in my bedroom. I have a Unifi U6-LR mounted to the ceiling about 50ft away and there is one wall (drywall) in between the access point and the Roku. I have a Plex server which is hardwired to my network. I have 2 separate WiFi networks, a 2G on channel 11 and a 5G on channel 153. I created 2 separate WiFi networks to force clients onto a specific band.
I am having trouble streaming ultra high quality 4K content to the Stream Bar Pro. The videos have a bitrate of 50mbit to 80mbit. When I monitor Plex when I try to play a video the actual bandwidth uses ranges from 90mbps to 150mbps. I cannot complete a speed test on the Stream Bar Pro when connected to the 5G network, but when I run a speed test on the 2G network I get 60mbps to 80mbps. The Stream Bar Pro reports Excellent signal strength when connected to either network. If I do a speed test on my iPhone standing next to the Stream Bar Pro I get 95mbps on 2G and 450mbps on 5G.
I have a Roku Ultra in my great room hardwired and I have no issues streaming the same content.
Plex is NOT transcoding. Everything is Direct Play.