Sometimes it happens that carriers misconfigure router or for other reasons some IPs are not reachable, the right way to diagnostic these problems is the following command:
mtr -o "J MX LSR NA B W V" -wbc 25 xx.xx.xx.xx
where xx.xx.xx.xx is the not reached IP.
In case mtr is not recognized you have to install the tool and installation is different depending the Linux version