Update, upgrade problem
After a while I tried to upgrade my Ubuntu server 11.04 with IspConfig installed.
It doesn't work, but it have already worked. I pinged security.ubuntu.com and this is the result:
PING security.ubuntu.com (188.8.131.52) 56(84) bytes of data.
After ctrl+c I got:
--- security.ubuntu.com ping statistics ---
63 packets transmitted, 0 received, 100% packet loss, time 62008ms
I've tried to modify /etc/resolv.conf with add OpenDNS's nameservers.
My server is behind router.