Unable to access Grafana UI on Kubernetes
To help drill down on what the problem is, I'd recommend seeing if the master is able to reach the pod at all. This'll help determine whether the issue is in your networking setup as a whole or just with the service routing from the master.
You should be able to verify whether the apiserver can reach the pod by kubectl attach -it --namespace=kube-system monitoring-influxdb-grafana-v3-grbs1 and seeing whether it's able to connect. If it can connect, then there's something wrong with the service routing. If it can't, then the master is having trouble communicating with the node.