PS4 disconnects again and again from the WLAN?

Hi, have recently the following problem: my PS4 always disconnects the connection to the Wlan, sometimes after 1 hour, sometimes after 15min…

the following in advance: It is not on the Internet / router. Have a connection test with my laptop and smartphone made, not even the connection was disconnected (in the same place). The router did not go crazy either. The ps4 is the only device that has problems with the connection! It always has 5 bars Wlan, nevertheless the connection separates regularly. Only she has previously worked without problems. Say in the same place it has worked for months, since recently but not more. What can I do to make the PS4 work again and maintain a working connection?

Let's see if there are firmware updates or something? KA if that even exists at consoles