Serviio

There is an app called IPTVX and they say "IPTVX supports the major formats and services including.... PLEX and SMB (for NAS/Servers and computers)."

I know Serviio will broadcast using DNLA but can it use SMB to broadcast?

No, SMB is a server-based file sharing method. Plex does not support SMB either. This app is apparently simply looking for either a network share location (via SMB) or has an internal Plex player app. The SMB share is simply offering a shared location that media files might be located in. The app is handling all streaming and playing functions. The SMB share is simply a place the media file resides.

DLNA is something completely different, with a client/server functionality. Serviio acts as the server, and provides the ability to stream the media and transcode any part of the media that might be unsupported by the player.

For iOS devices (and I believe also Apple TV) you have several choices of apps that will work with Serviio. One of course is VLC. This is a fantastic player with a less than stellar user interface. You don't get any metadata from the media server, but it will play almost anything, including captions. Another option is Infuse, but it's not free like VLC is. If you search the app store you'll find a large number of apps that support DLNA. The rare times I use my phone or iPad to stream from my Serviio server I use VLC, but as I said there are many more options.