I know this has been asked many times over time but I’m not able to get any solutions for this yet. I get max speeds over UPnP/DLNA like 350-400Mbps but only 50-75Mbps with SMB. Tried Legacy mode and the speed only increases to 65-75Mbps from 50Mbps. Both SMB1 and SMB2 is enabled on PC.
My router is R7800 and a Laptop with AX200 Wifi card. Both ATV and PC is connected to 5Ghz and the link speed is ~866Mbps and ~845Mbps on ATV. Most of the high bitrate movies buffers many times while streaming.
Are you streaming from laptop to Apple TV? Try connecting them both to Ethernet and see what speeds you get. Even if you can get link speeds that fast it doesn’t mean you can stream a movie that fast.
Did you try changing the “Streaming Cache” in the Infuse settings under playback to “Legacy” instead of Auto? This is different from the SMB related settings.
Could you try connecting via SMB instead of DLNA/UPnP?
This will generally be more reliable as Infuse has direct access to the files instead of relying on the DLNA server to provide the correct list of files.