Equipment (Modems,Gateways)
Modems, Gateways, and Networking Devices
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Visitor

Port forwarding seems buggy

I have a SMCD3G modem/router and 5 static IP addresses.  I'm trying to take advantage of the ability to forward ports from the public gateway IP to local IP addresses (192.168.8.x).  Currently I'm just testing with port 80 and 81 for web access.

 

It's working as long as I browse to the gateway IP from the Internet.  However if I do it from the local network it just hangs and times out.  It's as if the router doesn't know how to port-forward packets sent to its LAN interface.  If I change the incoming port from 80 to 81, same thing.

 

If that's the design, I think it's a bad one because users expect things to work in the same way no matter what their default gateway is for getting to the Internet.

 

Any suggestions?

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Visitor

Re: Port forwarding seems buggy

I found some enlightenment here:

 

Local computers (devices on the same subnet) must access the local server using the computers’ local LAN address (10.1.10.x, by default) instead of the public IP used to access it from external connections. Attempts by local computers to access the server using the external WAN IP address will fail.

Which leads me to ask, is there a router option without this problem? This is a pretty big deal for mobile devices.

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Re: Port forwarding seems buggy

Hello rodr and welcome,

 

Yes, it will work directly from the internet but not from within your internal network. If you want it to work from your internal network you must use the intrinsic static ip address like 50.65.75.85:80 or 50.65.75.85:81. The Comcast Gateway (CG) cannot provide address decoding directly to your internal network.

You can NAT a public CG static ip adress to a CG DHCP address between the range of 10.1.10.10 to like 10.1.10.199, for example.

 

Hope this helps you out.

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