Hi, does anybody knows how to stop beep sound when connection to net is down? I cannot find any controler of "beep sound" like S4 had. Thanks for any advice.
I don't think the S7's have a speaker to notify you when the internet connection goes down. I may be wrong but I though that's how they designed them.
I have two now .. both of them beeps like a hell

..so it does
I pulled the buzzer off on mine, and if you're careful it may actually be replaceable as the pins also come out. You'll likely void your warranty etc etc.
A small squirt of silicone sealant in the soundhole of the peizo element effectively hushes the loudness, but allows just a minute amount of audible tone to alert you if you are really close by. This probably would not void the warentee, but who knows. I'd live with it till the warentee dies, then do a tear down for cleaning of which, if it was bothering me, I'd de-solder the piezo element to PROPERLY disable the noise without stressing the circuit board.
You could always look into grabbing a router that has failover capabilities..... and tether your data connection to your cellular phone -- if one connection fails, it automatically switches to the back up connection.
I have something similar here. I have my cable connection, redundant #1 is the near by golf course's free WiFi ( they use DSL ), and redundant #2 is is a Virgin Mobile Cellular Hotspot.