Host down by no icmp


I’m a newbie here and a newbie with Nagios. The server is configured and most is working. But i have a problem, some of my servers are not able to send a ping. This is the router or provider blocked icmp requests.

I did a lot of searches here at the forum, and see a lot of this questions, but i did fix it. Can someone please help me with the step to step guide?

Greetings from Arjan, The Netherlands.