After having this issue only recently, and reading through these posts, the issue with controllers disconnecting when the system is using wifi, is directly related to the system using the same antenna. If you turn off wifi on the PS4 or connect it using an Ethernet cable, the problem goes away immediately. This has to either be a firmware issue or a problem on the board, as replacing the antenna did not change anything. Normally my system only runs with a wired connection, but I recently moved temporarily and my normal network connections will not be setup until my new house is built. I broke a controller in the process of trying to fix this. It was old, and I felt better for a few minutes, but Sony screwed up an update back in 2017 that still persists today, and seems to be a problem even with the new systems.