Equipment (Modems,Gateways)
Modems, Gateways, and Networking Devices
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New Contributor

The Port Forwarding with Public ip is not working internal network

Hello.

I have a problem with port forwarding after I changed comcast business modem.
I have comcast modem and own router connected to modem.
The comcast modem has public ip 71.59.xxx.xx and private ip 192.xxx.x.x
The router has wan ip address 192.xxx.x.x and private ip 10.x.x.x
All computer are connected to own router. The server computer has static private ip 10.x.x.xx
The network are same as before only different is new modem.
I changed the modem DMZ set to 192.xxx.x.x and changed firewall disabled.
I did not change anything own my router. (the router DMZ is set to 10.0.0.15)
If I put ip address 192.xxx.x.x on web browser, it connect to 10.x.x.xx. The port forwarding looks working but if I put public ip 71.59.xxx.xx then it show me comcast modem login.
I tried from my iphone with public ip then it connect to server 10.x.x.xx if I turn on WIFI on my iphone then it show me the comcast modem login.
I use the public ip address only for my job from internal and external network. the problem is if I turn on iphone WIFI and connect to internal network. the port forwarding is not working with using public ip.
The setting looks OK but why?
Please help.

 

[edited out all IPs]

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13 REPLIES 13
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Official Employee

Re: The Port Forwarding with Public ip is not working internal network

Hi there, thanks for taking the time to reach out to us about your port forwarding concerns and I am more than happy to help Smiley Happy Can you please send a private message with your name, the full address of the account, and phone number? 

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New Contributor

Re: The Port Forwarding with Public ip is not working internal network

I use same way to my home network. I have own my modem and router. The modem has public ip address and local ip address also I set router as dhcp server. The domain name assign to modem and the modem port forward to router and the router forwart to my web server.

http://oaks21c.mynetgear.com/ you will see welcome page. my internal network is no problem to connect to server with domain name.

 

 

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New Contributor

Re: The Port Forwarding with Public ip is not working internal network

Why my reply keep disappear?

 

mmmm. Someone called me today and he said no problem comast modem. It is because of double network.

He said use as bridge mode. The comcast know about this problem that is why use comcast modem as bridge mode.

no problem comcast modem use as bridge mode? mmmm. That is the modem problem.

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New Contributor

Re: The Port Forwarding with Public ip is not working internal network

The comcast know the problem but just don't know how to fix the problem.

I upgrade speed 28mb to 75mb about month now. They change my own modem to comcast modem for better speed up to 75mb and they will charge modem fee every month.

My own modem was working very good and it support speed up to 400mb but the comcast said it is not working and need to change to comcast modem. I feel like the comcast want to change the modem for monthly fee and extend their xifinity wifi network.

please can anyone help?

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Official Employee

Re: The Port Forwarding with Public ip is not working internal network

I understand what you mean and we do recommend switching to one of our modems that will support those speeds. I am so sorry for any frustrations. 

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New Contributor

Re: The Port Forwarding with Public ip is not working internal network

The old modem, I use for my home network and working fine I am happy with old modem.

 

 

My local network router is same setting as before I don't have to change any setting.

The port forwarding is working when I use local ip address (192.168.0.2) which is from modem dhcp provided.(My router local ip address is 10.0.0.1~)

Modem Public IP(71.xx.xx.xx) (192.168.0.1) --> Modem to router(192.168.0.2) --> router to computer (10.0.0.2~)

 

192.168.0.1 is modem local modem ip It was 10.1.10.1 so I changed as my old modem just in case.

(71.xx.xx.xx) forward to 192.168.0.2 (10.0.0.1) forward to server (10.0.0.15)

if i use from external network with ip address (71.xx.xx.xx) then working.

if i use from internal network with ip address (71.xx.xx.xx) then not working.

if i use from internal network with ip address (192.168.0.2) then working.

The domain name assign to the ip (71.xx.xx.xx) and it is working from external network but internal network.

Please someone know about network, advice me. Thank you.

 

 

 

 

 

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Official Employee

Re: The Port Forwarding with Public ip is not working internal network

It looks like you have Port Triggering rule on IP which needs to be deleted and then add port forwarding rule.

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New Contributor

Re: The Port Forwarding with Public ip is not working internal network

Capture.JPG

It is not enabled

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Official Employee

Re: The Port Forwarding with Public ip is not working internal network

Interesting and how long have you had this issue? 

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New Contributor

Re: The Port Forwarding with Public ip is not working internal network

The comcast changed our own modem to new comcast modem about weeks ago and the port forwarding is not working anymore after comcast changed modem.

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New Contributor

Re: The Port Forwarding with Public ip is not working internal network

someone in the comcast said set modem as bridge mode but I don't want to set modem as bridge mode if I do then I have to change all my local network settings during business. no way. too risky. 

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New Contributor

Re: The Port Forwarding with Public ip is not working internal network

Do I have to buy own modem?

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Official Employee

Re: The Port Forwarding with Public ip is not working internal network

Hi superdollarcity and thanks for reaching out! So since you have DMZ enabled let's try disabling it, using the NAT and reattempt. You can keep the firewall down for now if you used NAT for security temporarily. I also see that you mentioned having the device in bridge mode but you'd only need to do that with a separate router, so let me know if you're referring to the one built in to the gateway or a different one. Please let me know if that does the trick and if not, send us a private message by clicking on my handle (Comcast_Gina) and letting us know your name, the business name, the complete service address (including city, state, ZIP, suite number, etc), and the phone or account number. 

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