Major issues with Yamaha Musiccast

[Hintermann]

Just over 2 years ago I set up a Home Cinema system in the lounge of our apartment in Banglaore, India, where we spend 6 months of the year. This was based on a Samsung 4K TV, 4K BD player and the local Tata Sky satellite TV all of which are working fine with no issues whatsoever. The problem is with the WiFi based Yamaha Musiccast audio system, comprising of the following components:

- Yamaha RX-V685 Receiver (with Musiccast)
- Yamaha NS-P350 speakers (central, left & right; cabled)
- Yamaha SW300 subwoofer (cabled)
- Yamaha Musciccast 20 (locally WX-021) wireless surround speakers.

Of these, the wired front/central speakers and subwoofer work fine; but the Musiccast surround speakers do NOT. It was professionally set-up by a Yamaha technician and he has returned to try and resolve the issue repeatedly without success. What happens is that the Musiccast 20 rear speakers lose their Wifi link with the receiver and stop working whenever there is a power cut or surge (which is frequent in India) despite the fact that the powerful generator kicks-in in 12 seconds. Resetting the surround speakers afterwards is very hit and miss, the latter more often than not.

I tried plugging the powered rear speakers via voltage stabilizers but in vain. I then tried a UPS (Uninterrupted Power Supply) device to maintain constant power to speakers but that also failed to solve the issue. I finally removed the voltage stabilizers from the speaker plugs and plugged one of them onto the mains side of the UPS device and for the past 16 hours it has worked; I am keeping my fingers crossed.

But I am not sure if we have found the solution or if there is something else more reliable that we can try. Please help!