I have a network mixed of three X50 V1 1.8.0 and three BE25 V1 1.1.7 running in access point mode.

After the latest automatic upgrade of the firmware (both the X50 and BE25 were updated at the same time), the wireless backbone no longer works. All Decos work with wired ethernet backbone, but one X50 is placed in a location where no wired backbone is available. I moved this X50 Deco temporary to a location with ethernet available and then this deco works.

I started playing around and I changed the Main Deco from a BE25 to a X50 to see if that makes a difference. It made no difference. But now I can not switch the Main Deco back from the X50 to the BE25 as I get the error that the BE25 does not support Easymesh and the option to disable Easymesh fails consistently. Nowhere in the settings is an Easymeshoption and I have never used easymesh before. The disable option only appears when you try to change the Main Deco. It is nowhere else available, neither in the App (I use IOS) nor in the web interface.

How do I fix this? I have a broken Deco mesh wireless backbone and can no longer make the BE25 the Main Deco.

I have the suspicion that this is a problem with the X50 1.8.0 firmware. However, downgrade of the firmware is not possible once you have 1.8.0. 

Before this latest firmware upgrade, this setup was rock solid.