SMC's DHCP not broadcasting default gateway

[TnTheatre]

Our SMC modem/router's DHCP server is distributing LAN IP addresses correctly, but it's not distributing its own IP address as the default gateway. This, of course, effectively disables Internet access for anyone on dynamic addressing.

Anyone else run into this?

[Comcast_John · Accepted solution]

Hi TnTheatre.  Can you post a traceroute from one of the affected devices?  Devices behind your router should show your router as the default gateway with your router forwarding outside traffic to the SMC.  The first and last octet will suffice.

Thank You

[TnTheatre]

Hi, John; just saw your reply, thanks.The SMC is the router on this LAN, so I'm not sure I fully understand your question. There isn't a separate router between the SMC and the rest of the network.

[Comcast_John]

HI TnTheatre.  Connect a PC directly to a LAN port on the the SMC and test the connection to the internet.  Do not connect thru a switch or via a wireless access point.  There a couple of sites that will verify the originating IP address 

http://www.whatismyip.com/  and  http://ipchicken.com/.  The last octet of the gateway IP will identify as .19  (X.X.X.94)

Thank You

[TnTheatre · Accepted solution]

Hi, John. I think I may not have adequately explained the problem. A DHCP server should distribute a local IP, the subnet mask, the default gateway (OS X calls it "router"), and DNS address(es). My LAN client machines were getting all of these except default gateway/router (which should've been the LAN IP of the SMC modem).

As it turns out, the problem was that some jackass decided to enable the DHCP server on a Windows SBS machine on the LAN, with predictably hilarious results.

So it's not an issue with the SMC after all. Apologies for wasting your time, and I appreciate your replies.

[Comcast_John]

TNTheatre.  Thank you for the update.