I have a C9124AXE on Bridge Mode and it is a RAP. On the C9800 I configure the Mesh Profile, and Site Tag for their configuration. The other config that i set to the RAP is the static channel 157. For any reason when the RAP lost conectivity and then some time Join to the WLC, the RAP up with other channel different that I static configure. I dont know why the RAP change the static channel.