6120 setup

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6120 setup

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6120 setup
6120 setup
2022-04-27 13:11:01
Model: TL-ER6120  
Hardware Version: V3
Firmware Version: 3.02

I need to connect a comcast cbr-t router/modem to a tp-link er6120.

The comcast router has a static external ip address that I must be able to reach.

The comcast router is currently set up to hand out ips in 192.168.1.???.

 

I have 6 ports forwarded on this router and they are all accessible through the static external ip address.

 

Comcast has informed me that if I put the router in bridge mode I will lose my static ip and wifi.

I need the static ip. I can live without the wifi.

 

I wish to use the er6120 to act as a failover device for 2 different internet providers.

I don't need load balancing or vpn.

 

I would like to keep all workstations, printers and other devices on 192.168.1.???.

 

I was doing the failover manually with 2 router/modems set up identically and just unplugging one from the network and plugging the other one in.

It worked, it just wasn't automatic.

 

I set the er6120 lan to 192.168.2.1.

 

I set wan1 to static and entered my external static ip, gateway and dns numbers.

I don't get internet access.

 

It tried dynamic ip.

It picks up
192.168.1.77
255.255.255.0
default gateway 192.168.1.1
dns 75.75.75.75
dns 75.75.76.76

 

All of my workstations that were picking up an ip from 192.168.1.??? are now picking up 192.168.2.???.

I assume that the er6120 is handling all dhcp.
It gives me internet access on my workstations that pick up a dynamic ip in 192.168.2.???.
I get no internet on any of my statics in 192.168.1.???

What do I need to do to get internet on all workstations?

How can I keep all of my devices in 192.168.1.1?

I realize that I have a double nat going on.

I don't care about the port forwarding right now.

I just want to get wan1 working for all devices.

I will deal with double nat port forwarding and adding wan2 when I ge wan1 working.

 

 

 

 

 

 

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#1
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4 Reply
Re:6120 setup
2022-04-28 13:18:04

  @gjunk 

 

Your current topology is indeed double NAT, and as far as I know, the NAT function of the ER6120 cannot be turned off.

Unless you have a DHCP Server of your own in your LAN, otherwise the ER6120 is not a DHCP Server, and the clients connected behind it will have no device to assign IPs to, and the clients behind it cannot get IPs from your comcast router due to NAT blocking.
In my opinion, the principle should be like this.

Just striving to develop myself while helping others.
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#2
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Re:6120 setup
2022-05-02 11:35:08

  @gjunk

I set the er6120 lan to 192.168.1.1.

I set the comcast router lan to 192.168.2.1.

I set the comcast router into passthrough mode by turning off DHCP and opening the firewall.

I can't use bridge mode because it causes the router to lose its external static ip. This is  a comcast issue.

 

I set the comcast router on wan1 to static 192.168.2.2,

It won't pick up a dynamic because there is no dhcp from that router.

 

All workstations are picking up an ip from 192.168.1.???.

I have internet on all workstations.

I set the Network->Lan->DHCP server to hand out ips in the 192.168.1.2-254 range.

The er6120 must be providing the dhcp to the workstations since the the non statics are picking up in its range.

I turned port forwarding off in the comcast router because it is not providing dhcp.

I created a virtual server to forward port 21 to 192.168.1.238.

ID Name Interface External Port Internal Port Internal Server IP Protocol Status Operation
 
1 ftp WAN1,WAN2 21 21 192.168.1.238 ALL Enabled  

I can reach the ftp server on the internal network.

 

I can't reach the ftp server on the external ip address or through domain name.

 

What do I need to do to get to the external ip?

 

 

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#3
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Re:6120 setup
2022-05-04 02:27:29

  @gjunk 

 

I actually have never done it, but try something like this.

 

Comcast Router:

WAN set by Comcast to your public static IP address

LAN set to 192.168.2.1.

 

TP-Link Router:

WAN set to 192.168.2.2 (same subnet as Comcast LAN)

LAN set to 192.168.1.1 and the DHCP server enabled.

 

Then, set up port forwarding for the FTP server on both routers. Note that the Comcast router should forward it to the TP-Link router WAN IP address, not the FTP server directly. 

 

 

Kris K
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#4
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Re:6120 setup
2022-05-04 11:53:03

  @KJK 

Thank you.

I got it all working.

 

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#5
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