Unfortunately it seems that the Grafana stack with Influxdb and Telegraph is not stable enough on my raspberry pi.
An issue that could cause this, is the SD-card , it’s speed and durability.
Even after disabling Grafana. the pi running that , which i also used as a webserver, crashes. So a conclusion at this time is that de SD card is having some issues. New higher speed SD-card has been ordered. Until then , the Grafana portal has gone offline unfortunately.