Wifi not working


I recently supplied 8 screenly OSE Pi 3Bs to a site and when they tried to setup with wifi they were able to connect to the pi and choose a wifi network but when rebooted they were unable to log on to the wifi even though they had the password. This happened on 6 of the 8 Pi’s. In the office here I recreated the fault, I then connected up via the LAN socket on the Pi to the same network the AP was on and then when I disconnected the cable the Pi was then able to connect to the wifi. Is this a known issue? The Pi’s were supplied in Oct last year and the version of Screenly was production@d12df55.