I have a setup with two different models of deco: X20 (main deco + two satellites with backhaul) and two M4R (EU) satellite slaves one with backhaul and one through MESH. I have used this setup since June, 2020 without any problems. Now, when finally updating the new firmware for X20 and TRIED to update the new firmware for M4R, the M4R decos are constantly dropping out of the network. They may stay in the network like 2 mns and drop out for 10-20 mns. I tried to update the firmware for M4R (1.4.2 build 20200727 rel. 37987), but it did not go through, even if I received after udgrade a notice that they are up to date. When opening deco app again, it showed they must be updated and suggested the same firmware which I already installed. I tried many times without success and finally tried through download center using browser, just to see that there is not the same version of firmware available... (see above).
So, I had to delete these two M4Rs out of the system, because they are not working and causing problems for other devices.
Any advice what to do? This really is happening after the firmware updates, nothing before that.