When I request an echo reply of my public IP from my local network I get an ICMP timeout; on the other hand, making an echo request on my public IP from a machine from the internet (connected via ssh) returns an echo reply.
How do I know my public IP? I went to www.whatismyip.net. My ISP has assigned me a dynamic IP address, which is shared one (I was told by my ISP).
My friends don't reproduce this behavior with their networks, which means they get an echo reply pinging their public IP.
When I call my ISP they tell me that I should subscribe for a business plan which costs US$10 monthly extra and they talk about a static IP, so I just hanged up the phone. Morons.
What causes that I don't get an echo reply? How can I fix this error? I'd appreciate any feedback.
EDIT: My router is a D-Link DI-624.