DD WRT loses WAN connection. Why does releasing and renewing the DHCP reestablish connection?
I have actually run in to this exact same problem myself, several times. (In one case the problem turned out to be an improper power supply on one of my routers, so much sure you check ALL the basics first.)
As for who's at fault, I would blame consumer level equipment. These little Netgear/Linksys/etc boxes have never been the bastion of reliability, and there's also nothing elegant about them.
- Check your WAN IP address. I've had junky modems temporarily hand out a 192.168.100.x address to my router while it picks up a proper IP address. Sometimes my router would get stuck here, rather than picking up the public IP.
- If you want to drill down in to what's going on there, shove a hub (not a switch) in between the router and modem, then sniff the packets from a computer using Wireshark or Microsoft Network monitor.
- You could also use tcpdump from your DD-WRT router for troubleshooting
- It can also be helpful to enable logging on the DD-WRT router and take a look at what events pop up.
- Personally, I would stop fighting with it and go ahead and set up your script. Check 8.8.8.8, release and renew if that's down, and if that doesn't work reboot. Problem solved. If the problem isn't solved, smash your modem in to tiny little pieces and get a new one.
As noted by @r.Tanner.F , consumer-grade hardware can have issues.
One of the most common is they do not tolerate heat or bad power well.
Make sure there is ample air circulation and avoid stacking other hardware like modems or switches.
Power is best addressed by installing an UPS so that you get a steady 120V (or 230V). I have seen many clients with issues solved with a good UPS. Spikes are usually not the issue but rather brownouts and low voltage in general. It seems to send the device into a weird state where it may not work at all or some functions fail.
In any case, a good UPS is always a good idea.