Wifi connection problems MBL / TVL in combination with Iphone / Ipad

The WD support was truly great! They called twice. The first time for trying to solve te problem and a week later to ask if the probolem is still solved. 

The WD suggestion was to set my WD devices as static IP >.80 and > .101 

Unfortunately the disconnenction problems with the Iphone’s remain (set as dynamic IP by the way).

Could there be any other solution? Or am I deemed to buy antother router? (don’t have a  clue if this solves the problem).