I have 2 Deco M9 Plus in my set up, in AP model. One slave, one master. The set up has been successful for a year.
A few days ago the slave speeds started acting up and now I can only get 50-60Mps vs 950Mps (I'm on a gigabyte line). The slow slave speed is apparent for both wired and wireless connections. The master continues to give me 950mps on wired and about 280Mps on wireless.