What port is your dlna server listening on? miniDLNA listens on port 8200 then communicates back to VLC on port 1900 UPD.
________ ______
| |<-------- 8200 TCP -------<| |
| DLNA | | VLC |
|______|>-------- 1900 UDP ------->|______|
On the computer with VLC the outgoing request on 8200 is OK as default on firewalld from EnOS is all outgoing ports are open.
On the computer with VLC, the incoming communications needs firewalld port 1900 UDP opened.
No guaranty that the DLNA computer is listening on port 8200 TCP, it may be different.
Pudge
EDIT:
Sorry, I use VLC so it just came to mind while making the diagram. It works the same for Rhythmbox. Besides, VLC fits in the box better. 