PS4 will only recognize one external storage drive at a time You need to check whether the drive was previously formatted for external storage.You need to cross-check whether the external HDD is connected directly to the PS4 via one of its USB ports which apply to hub USB external hard drives also.Cross verify that your external hard drive is compatible with PS4 standards.As the PS4 system doesn't recognize wireless external hard drives, make sure PS4 external hard drive has a wired connection.If it is working there perfectly fine, check the other point(s) and make sure whether it needed to be replaced at this point itself. Connect your External HDD to your PC and check for any damages.
