There is an easy test to perform:
On your client box, disable the tuners.
Use the same channel list that the one on your server box.
In the client configuration define as remote fallback STB the server that you want.
Now you should be able to zap on the client and it will use the server tuners, test if subtitles are working fine.
Pr2
Yes!
After Enable fallback remote receiver, add the IP address of the box on the next line Fallback remote receiver URL and using the same chanel list from server STB, now subtitles works
All of you guys, I really thank you.