said by DrDrew:
That doesn't mean the gateway is busy. It means the card management processor may be configured to put ICMP on a lower priority or the card manager is busy, but that frequently doesn't affect the packet passthrough on the gateway to another router.
So, it's busy tending to other higher priority requests. Before Sandy, the gateway answers within 30 ms anytime of day. How can you explain that?
Again, though it could be private addresses are blocked at the WAN port of your home router.
Like what I've said, the gateway has been responding everytime before the storm and as far as my network, the gateway is always seen as a public ip(68.xx.xx.xx).