Just general devices like laptops, mobiles, tablets and chromecast.
The only problem with plex is that transcodes which i'd rather it did not do. I have set it to play the original file over the web interface but using the plex app on my phone, tablet or laptop pushes the cpu to maximum. I'd rather play the original file without conversion.
The other option is to use the synology but it doesnt index the media often enough.