The routing has changed after the router with the IP address 188.8.131.52. The default gateways for the machines seem to be the same before (good) and after (bad) so ARP isn't the issue.
New routing may not necessarily be bad. They could be part of the design. Traceroute may be blocked as part of that new design too.
Can you ping the target IP address or get to it on port 80 with telnet (I'm assuming this is a webserver IP)?