Samsung Q60 doesn't remember Wifi connection

I have connected my Samsung Q60 to WiFi via WPS. This works fine so far. But when i restart the TV, i have to reconnect every time via WPS again, since the TV doesn't remember the WiFi connection. If it is connected, it works fine so far. If i look at the router, i can see, that it is using always the same MAC address to connect, so this is not the issue.