All sm’s are within less than a 1/4 mile of the ap.
I went back to the site, AP was on a DFS channel. It was in automatic channel selection, which I have since remedied, 2 190’s were in factory firmware and associating to the access point. The other 2 upgraded to 3.5.1 and stopped communicating on the DFS channel. I have heard that the 190’s are not approved for DFS channels but that does not make since as they were associating on factory firmware