A couple of things to watch out for. The sqlite3 db should be updated when you change the file (speech.mp3) outside of minidlna. Normally this happens when you move a file into the minidlna directory. Will it pickup a update to an existing file? I suspect it won't and I suspect this is what you are seeing. If so, try removing speech.mp3 and then copy in the new one. I would also worry that the client may cache files if it doesn't think anything has changed.
A couple of things to watch out for. The sqlite3 db should be updated when you change the file (speech.mp3) outside of minidlna. Normally this happens when you move a file into the minidlna directory. Will it pickup a update to an existing file? I suspect it won't and I suspect this is what you are seeing. If so, try removing speech.mp3 and the copy in the new one. I would also worry that the client may cache files if it doesn't think anything has changed.
Have you tried looking at error messages and logs? Perhaps run it from your mint...
You could also accept that DLNA (minidlna) is not really a real-time streaming ptotocol....
I can't speak to cross compiling minidlna but if the TPL-wd3600 runs a debian derivative...