I have 2 computers now: downloader (asus at4nm10t-i) with debian and desktop (asus sabertooth 990fx) with gentoo in the same network under NAT even with the same ethernet card: RTL8111E. driver r8169 is compiled as module on both computers. Sometimes in evenings desktop cannot connect to google and all its services like now:

curl -v http://www.google.by

on downloader it received server's answer immediately. on desktop it hanged and when I ran in other terminal:

netstat -ntp | grep curl
>>tcp 0 1 192.168.0.7:54126 173.194.35.191:80 SYN_SENT 4876/curl

after 1-2 minutes it received server's answer. I was tried to change ip of network, mac address of desktop but nothing changed. When I was trying to connect to another services except google:

curl -v http://www.yahoo.com

both computers received answers immediately! Only when I rebooted desktop it begins to work with google services correctly

I cant understand what is this bug related to. In which bugtracker should I post this: r8169 or linux kernel or google?

PS. Desktop was checked with memtest: 5 passes - no errors