There is nothing that can help you at the published location of this mystery cache. Somewhere inside a circle around this waypoint (radius 500m) you will be able to capture SSID GC-Bezoeker (it used to be KroonBezoeker).
To calculate the final location of the cache, you need to find the corresponding BSSID (it contains a D).
Final cache location: N50 51.A E4 17.B
A is equal to the sum of the first 3 bytes of the BSSID and -239.
B is equal to the sum of the last 3 bytes of the BSSID and 429.