How to connect to modem through router WAN port?

[davidcmc]

I have the following setup:

Fiberhome modem in BRIDGE mode (LAN IP 192.168.1.1), connected to the WAN port of a TP-Link WR940N v5 in ROUTER mode (NAT and DHCP on, LAN IP 192.168.0.1, stock firmware).

The WR940N authenticates the PON connection by PPPoE and works as expected.

However, I can't connect to the Fiberhome web gui by typing 192.168.1.1 on the web browser. It works if I connect my PC directly to the modem.

Back in the days that I've used a cable modem (also in bridge mode) of another ISP, I was able to access the modem web gui simply by typing its LAN IP in the web browser. The setup was identical to the current one.

Any suggestion?

 

[jsmithepa]

Not sure why this is not working.

But I can say modem is not in bridge mode. If in bridge mode you would have an public IP, not an RFC1918 IP. Currently modem does NAT, and your Tp-link is also doing NAT, u got a double-NAT situation.

 

[bill001g]

It maybe because it is PPPoE. This is kinda a form of VPN. To a point I am kinda surprised a cable modem can intercept the traffic when you consider it technically is on the wrong subnet. I suspect the pppoe connection is between your router and the home office equipment and not the modem. It maybe that it is just too complex for the modem to insert itself into that traffic.

 

[davidcmc]

Not sure why this is not working.

But I can say modem is not in bridge mode. If in bridge mode you would have an public IP, not an RFC1918 IP. Currently modem does NAT, and your Tp-link is also doing NAT, u got a double-NAT situation.

The modem is really in bridge mode. Note that the 192.168.0.1 I've mentioned before is the LAN IP of the router, not the WAN IP.

It maybe because it is PPPoE. This is kinda a form of VPN. To a point I am kinda surprised a cable modem can intercept the traffic when you consider it technically is on the wrong subnet. I suspect the pppoe connection is between your router and the home office equipment and not the modem. It maybe that it is just too complex for the modem to insert itself into that traffic.

I've managed to make it work.

TP-Link stock firmware has a feature called "secondary connection". According to TP-Link (https://static.tp-link.com/1910012046_TL-WR940N_V5_User%20Guide.pdf), WAN secondary connection is "available only for PPPoE connection. If your ISP provides an extra connection type, select Dynamic IP or Static IP to activate the secondary connection."

To summarize:
Fiberhome modem in BRIDGE mode: 192.168.1.1
TP-Link in ROUTER (NAT and DHCP enabled): 192.168.0.1
TP-Link secondary WAN connection: 192.168.1.2

Also note that Fiberhome is connected to the WAN port of the TP-Link router.

I can now access Fiberhome by typing 192.168.1.1 in the web browser normally.

 

[jsmithepa]

Cool. Grad u figure it out.

My cable modem kinda works like that, although it doesn't do PPPoE, it gives me a public IP, but then it says, go to this 198 IP for management, I just blindly followed and didn't give it a second thought.