10.6 Server's Firewall Blocks It's Own Internet Connection

Question

I had this problem about two years ago when I was trying to run 10.6 on my home server (Mac mini) for the first time. Eventually I gave up, reverted the mini back to 10.5, and ram problem-free for years. When 10.7 came out, I tried to upgrade the mini to that. That didn't go well either, but mostly due to Lion missing many many features (suprise!). So I figured that 10.6's problems were fixed by now, and gave it another shot. It went fine and I've been running for about a month problem free (or so I thought). But now it's offline again. I finally found one other person on another forum that had the EXACT same problem as me. And reading this description, I realize that I have been having problems all long, I just assumed they were my ISP's problems, not my own.
So here's what happens. The firewall in 10.6 server will "freak out". It will be running normally, then suddenly it will go haywire and block everything. And I mean everything. My computer won't even be able to get an IP via DHCP. Everything is blocked. But as soon as you stop the firewall, everything works normally. You can even modify the firewall rules, and set it up so there are NO deny rules, and EVERY connection to and from every host is set to allow. And the firewall still blocks everything. This is the same exact thing that happened 2 years ago when I first tried to run 10.6 Server on my mini. The difference is that back then, this would happen either immediatly, or within a day. This time around, with 10.6.8, it took about a month before suddenly, without any provocation, all internet connections stopped.
I've had this happen on multiple computers. I don't do anything special, I just set up a basic firewall scheme where everything in the LAN range is allowed, and everything from "any" is allowed only to service ports I'm running. The basic gateway setup. Now I was running 10.6 Server on my laptop (for netbooting) and it would do the same thing. But because my laptop wasn't acting as a gateway, I could just turn the firewall off (you need the firewall for NAT). My mini server IS acting as a gateway, as was another mini I set up for a client of mine (that eventualy I changed over so they were running off an airport, and the mini server was just a client. But I don't want that setup at home, I want my mini to be the router).
I have verizon Fios internet. 25/25, it's great. The ONT is in my basement, and it's plugged into the same fused outlet as our freezer. From time to time, when the power goes out, it trips that breaker and the outlet goes dead. My itnernet is gone and I have to go reset the outlet. Once I do, my mini won't get an IP from Verizon until I reboot the mini. Not once. Not twice. Usually 5-10 reboots, and suddenly it will get an IP. I always assumed this was a verizon problem. Until I read someone else's post about this same problem. Turns out, that's the firewall blocking DHCP again! If you turn the firewall off, you don't have to keep rebooting, it will grab an IP right away.
At least I'm not crazy! So what is going on here? Does anyone have any idea what is going on with my firewall, or how I can fix it?
Lastly, after 4.5 hours of complete inability to get an internet connection with the firewall on, it just started working again. I now have fully functional, normal internet. I find it hard to believe 10.6 has a firewall that is simply broken. I find it even harder to believe I'm imagining things, or that I've had fluke after fluke. Something is going on with 10.6 Server.

Answer 1

The DNS skapegoat just doesn't make sense.
Why would "improper" DNS cause OS X's firewall to block all network connections? Even the server's ability to make it's own DHCP connection?
As far as a router, I don't want to use a cheap unreliable residential router. I have a home file server that, aside from running 10.6, makes a super reliable router. And port mapping aside, OS X Server's DHCP server is great to use. Rock solid. It makes no sense to run a cheap residential router when I have a home server. Then every 6-18 months, I get to deal with that router slowly failing, as my internet connection gets slower and slower. No thanks.
So back to this firewall issue. I've talked to Apple aobut this before, and they give the same generic "DNS has to be right" answer to basically every problem I've ever had with 10.6 Server (hinting at endless CalDAV problems). But no one has every explained what that specifically means, or how something like wrong DNS (whatever that even means) can cause the firewall to block everything. This just makes no sense to me. And this especially does not explain why, after 10 reboots or so, everything just magically starts running normally.
I just had an incedent today where I woke up to no internet. I rebooted 3 times. Each time, I either got a self-assigned IP address, or the ethernet interface would toggled between "unplugged" and "no-ip". I could turn the firewall off and the server would INSTANTLY start functioning normally. I'd happily run without a firewall, and just turn all services I'm not using off. However NAT needs the firewall, so without the firewall, the Server is the only Mac on the network that has an internet connection. So I kept rebooting and rebooting, and I think about 8 reboots later, like magic, the server came up, grabbed an IP, and everything started working normally.
Also my IP through my ISP is dynamic, and that isn't going to change. So yes, I am trying to use OS X Server as my router on a dynamic internet connection. I've been doing this since the days of Mac OS X Server 10.1. Only 10.6 has had any problems at all.
So really, "10.6 is more picky about DNS" isn't an answer to this problem. Or, at least, it's not a sufficient answer. I need much more information than that.