Works perfectly for me...
Did you get an error message or make a change to the DNS on the router interface?
It seems I can't reach the site...
$ ping www.redhat.com
PING e3396.dscx.akamaiedge.net (18.104.22.168): 56 data bytes
64 bytes from 22.214.171.124: icmp_seq=0 ttl=57 time=8.982 ms
64 bytes from 126.96.36.199: icmp_seq=1 ttl=57 time=8.889 ms
--- e3396.dscx.akamaiedge.net ping statistics ---
2 packets transmitted, 2 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 8.889/8.935/8.982/0.047 ms
$ ping www.cepv.ch
PING www.cepv.ch (188.8.131.52): 56 data bytes
Request timeout for icmp_seq 0
Request timeout for icmp_seq 1
--- www.cepv.ch ping statistics ---
3 packets transmitted, 0 packets received, 100.0% packet loss
Have you tried other sites which do not work, or is this site an isolated case?
Have you ever tried to restart the Internet Box?
If so, if it is relevant to you, I would briefly ask Customer Service if there is a problem in your line or with the Internet Box.
It seems a bit strange to me that only this page does not work.