I use a NanoPi M4 V2, which has a SATA hat accessory. It will support 4 HDDs and even power them if they are all 2.5" drives, or you can do what I did and use 4x 3.5" drives in a simple cheap cage and a separate 12V 8A power supply on the side to power the lot.
No problems streaming 4K x265 content using Plex (with a compatible Plex Media Client)
I use a NanoPi M4 V2, which has a SATA hat accessory. It will support 4 HDDs and even power them if they are all 2.5" drives, or you can do what I did and use 4x 3.5" drives in a simple cheap cage and a separate 12V 8A power supply on the side to power the lot. No problems streaming 4K x265 content using Plex (with a compatible Plex Media Client)