Here’s a little update.
I started by adding all the Cisco APs to my own home librenms, after a short time to come graphs with correct data in it…
Then I made a new virtual server with a fresh installation of librenms (ubuntu 18.04 + Nginx), after a short time came fine graphs with data from the Cisco APs … I thought then it had to be something with the old server so I emptied the folder /opt/librenms/rrd for content and after a short time came graphs with data from all devices including the Cisco APs … Now it works but why there was no data on the graphs until after I cleared the folder I can’t explain.