@asharda 

Hi, welcome to the community.

Downgrading from 1.2.1 to 1.1.1 is crossing different firmware platforms so it could not be completed via web UI directly.

Since it is still unclear whether the disconnection is related to the latest firmware, it would be better if we stay on the latest firmware.

Maybe you could help me check the following details first to see whether we could find the problem.

1. Have you noticed any satellite Deco XE75S turn flashing red?

2. How often would they drop out from the main Deco?

3. Are these two satellite units wirelessly connected to the main unit?

By the way, would they come back to green/online automatically later?

Wait for your reply and best regards.

  @asharda 

Hi, Thanks for the update.

I would follow up on your case via email and consult the engineer for more advice.

By the way, I noticed you mean the LED on the satellite XE75 is yellow/orange, instead of red and if it is indeed the first color here, it looks like Deco randomly restarted itself which might have caused the disconnection. Would you mind helping me confirm the LED color?

Wait for your reply and best regards.