Some devices will support subtitle files by default, and for those that don't Serviio can hardcode them on the video while streaming. However, this increases CPU usage and will not work for low powered NAS devices.
You can reach your media files on most smart TV's, some gaming consoles (PS3, PS4, XBOX360 and XBOX One), Android and iOS smartphones, Blue-ray players, DirecTV DVR, Roku and many more.
If your wireless router is in another room, larger HD files can "stutter" a bit, especially when there are a lot of high-pitched sounds in the background.