License server gets unreachable time to time

I have a portworx disconneted (air-gapped) cluster configured with PX-Essential license.
I have provided following env variables in portworx-operator deployment.

    - name: PX_HTTP_PROXY
      value: http://xxxx:8080
    - name: PX_HTTPS_PROXY
      value: http://xxxx:8080
    - name: OPERATOR_NAME
      value: portworx-operator
    - name: POD_NAME

The proxy is reachable. Also i can curl to billing and logly endpoints via proxy.
The env is correctly set inside operator pod.

The lincense was showing green yesterday, but after 24h lease expired 2 of the 3 nodes could not renew the license and are failing since then.

How to initiate license renewal on demand and where as PX_PROXY needs to be set?