Headless Mac Mini, acting as NAT router, goes to sleep. Why?

Hello there!

I am running a Mac Mini as a headless NAT router. As described in Apple's (pretty hidden) documentation, there is no NAT routing anymore in the Server.app. And unfortunately, the Internet Sharing option is broken; it wouldn't serve a lookup domain alongside the DNS servers, which makes Non-Apple based systems unable to use the network, as they all seem to rely on that specific part of the DHCP lease...kinda weird, but okay. So, I created my own NAT rules and used the natural pfctl stuff.

Now, I leave this server at home and keep it running so it can act as a cache server too. But in that house is another person (with no clue about OS X) and who uses the server as his internet access. Today, he reported that the ping was about 1000ms. Usually, we get 29ms. Once I got home, I VNC'd into my Mac Mini, and also kicked off a ping command. The result, was horrific.

$ open vnc://server.local; ping google.de PING google.de (173.194.112.120): 56 data bytes Request timeout for icmp_seq 0 64 bytes from 173.194.112.120: icmp_seq=0 ttl=53 time=1037.329 ms 64 bytes from 173.194.112.120: icmp_seq=1 ttl=53 time=759.511 ms 64 bytes from 173.194.112.120: icmp_seq=2 ttl=53 time=1341.813 ms Request timeout for icmp_seq 4 64 bytes from 173.194.112.120: icmp_seq=3 ttl=53 time=2007.715 ms 64 bytes from 173.194.112.120: icmp_seq=4 ttl=53 time=2004.524 ms 64 bytes from 173.194.112.120: icmp_seq=5 ttl=53 time=1044.315 ms 64 bytes from 173.194.112.120: icmp_seq=6 ttl=53 time=1168.518 ms 64 bytes from 173.194.112.120: icmp_seq=7 ttl=53 time=567.374 ms 64 bytes from 173.194.112.120: icmp_seq=9 ttl=53 time=1212.561 ms 64 bytes from 173.194.112.120: icmp_seq=10 ttl=53 time=946.760 ms 64 bytes from 173.194.112.120: icmp_seq=11 ttl=53 time=671.430 ms 64 bytes from 173.194.112.120: icmp_seq=12 ttl=53 time=862.685 ms 64 bytes from 173.194.112.120: icmp_seq=13 ttl=53 time=779.299 ms 64 bytes from 173.194.112.120: icmp_seq=14 ttl=53 time=377.574 ms 64 bytes from 173.194.112.120: icmp_seq=15 ttl=53 time=933.683 ms 64 bytes from 173.194.112.120: icmp_seq=16 ttl=53 time=850.602 ms 64 bytes from 173.194.112.120: icmp_seq=17 ttl=53 time=1078.193 ms 64 bytes from 173.194.112.120: icmp_seq=18 ttl=53 time=749.243 ms 64 bytes from 173.194.112.120: icmp_seq=19 ttl=53 time=551.680 ms 64 bytes from 173.194.112.120: icmp_seq=20 ttl=53 time=1094.805 ms 64 bytes from 173.194.112.120: icmp_seq=21 ttl=53 time=605.193 ms Request timeout for icmp_seq 23 64 bytes from 173.194.112.120: icmp_seq=22 ttl=53 time=2030.361 ms Request timeout for icmp_seq 25 Request timeout for icmp_seq 26 Request timeout for icmp_seq 27 Request timeout for icmp_seq 28 Request timeout for icmp_seq 29 Request timeout for icmp_seq 30 64 bytes from 173.194.112.120: icmp_seq=27 ttl=53 time=4451.923 ms 64 bytes from 173.194.112.120: icmp_seq=28 ttl=53 time=3895.684 ms 64 bytes from 173.194.112.120: icmp_seq=29 ttl=53 time=4004.588 ms 64 bytes from 173.194.112.120: icmp_seq=30 ttl=53 time=4659.981 ms 64 bytes from 173.194.112.120: icmp_seq=31 ttl=53 time=4276.043 ms 64 bytes from 173.194.112.120: icmp_seq=32 ttl=53 time=3715.686 ms 64 bytes from 173.194.112.120: icmp_seq=33 ttl=53 time=2824.368 ms 64 bytes from 173.194.112.120: icmp_seq=34 ttl=53 time=2979.580 ms 64 bytes from 173.194.112.120: icmp_seq=35 ttl=53 time=2792.215 ms 64 bytes from 173.194.112.120: icmp_seq=36 ttl=53 time=2166.811 ms 64 bytes from 173.194.112.120: icmp_seq=37 ttl=53 time=1201.330 ms 64 bytes from 173.194.112.120: icmp_seq=38 ttl=53 time=541.141 ms 64 bytes from 173.194.112.120: icmp_seq=39 ttl=53 time=2120.052 ms 64 bytes from 173.194.112.120: icmp_seq=40 ttl=53 time=1597.928 ms 64 bytes from 173.194.112.120: icmp_seq=41 ttl=53 time=1003.694 ms 64 bytes from 173.194.112.120: icmp_seq=42 ttl=53 time=118.839 ms 64 bytes from 173.194.112.120: icmp_seq=43 ttl=53 time=102.392 ms 64 bytes from 173.194.112.120: icmp_seq=44 ttl=53 time=212.062 ms 64 bytes from 173.194.112.120: icmp_seq=45 ttl=53 time=254.563 ms 64 bytes from 173.194.112.120: icmp_seq=46 ttl=53 time=27.062 ms 64 bytes from 173.194.112.120: icmp_seq=47 ttl=53 time=23.724 ms 64 bytes from 173.194.112.120: icmp_seq=48 ttl=53 time=22.430 ms 64 bytes from 173.194.112.1 ...

As you can see, it took me a while to log in, But at icmp_seq=41 to 42, I finally logged in. Now you see how the ping goes down dramaticaly.

So I checked my Engery Saving settings; my HD's don't go to sleep, and my sleep it actually turned off. Confusing O.o I also am running the Caffeine app from the App Store, as I hoped it would change something, since this happened before...but it didn't.

Does anybody know, what I am missing out? Would be very great to know.

Kind regards, Ingwie!