Access ISP modem from OpenWRT router

Hello everyone! I am new and honestly very happy I came across this project. Awesome to see so many people create something so useful!

I bought a bit of hardware for my parents from recommended ToH. Everything worked great. Currently I have my ISP's router in bridge mode as a dumb modem. Connection is DSL. My openwrt x86 router receives the wan IP address and gets internet access, I've configured my WAN to PPPoE with login and password and it works.

The only issue is I cannot access my ISP's modem from my router. I followed this guide https://openwrt.org/docs/guide-user/network/wan/access.modem.through.nat but for whatever reason any IP I set for that new interface just forwards to Luci instead of my ISP modem interface.

Also curiously on the overview page network gateway is 192.168.100.1 even though the ip address of the modem is 192.168.1.1 when I connect to it directly.

Does anyone have any ideas?

The router wan port shares a trunk connection with the dsl modem, modem website on untagged
vlan1 and pppoe internet on vlan35. This lets me view/modify the modem. Using a smart switch makes a router on a stick with a single port router, like a raspberry or banana pi.

Hi, thanks a lot for responding.

I am not sure how to set this up. I think at this point my modem is not a Vlan aware device. Not very familiar with Vlans yet but do numbers intrinsically mean anything or there are supposed to be rules assigned?

Can you maybe explain what is happening maybe I will think of something? Maybe this can be resolved with a firewall rule

Hi

this is problem nr#1
modem management subnet is 192.168.1.x/24
and your OWRT install, by default have same 192.168.1.x/24 range on LAN
first thing, before you try anything else, is to move your OWRT lan to another subnet
for ex: 192.168.5.1/24

other problem/WAN config could be solved only after first step

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It took many hours to get familiar with the dsl modem. Here are the results:
In the TekSavvy SR501 dsl modem, the default lan ip is changed from 192.168.1.1 to 192.168.5.1, to avoid conflict with openwrt's default 192.168.1.1
logging into the SR501 at http://192.168.5.1/admin/
Advanced Setup / WAN Service is set to bridged mode, without untagging vlan35 to vlan1; getting a WAN ip takes 2 seconds this way, versus 2 minutes with vlan35 untagged to vlan1
Wide Area Network (WAN) Service Setup: Interface ptm0.1, Description br_4_1_1, Type Bridge, Vlan8021p N/A, VlanMuxId N/A, VlanTpid N/A

Hi, thanks for responding.

I've changed my Lan to 192.168.50.* originally openwrt router was occupying the same address as my ISP modem. They're on different networks yet it is still unreachable. Maybe it's the firewall rules since modem is technically in the WAN zone?

Ok

could you paste here
cat /etc/config/network
and redact your PPPoE user/pass

Of course, thanks for taking the time to look through that

root@OpenWrt:~# cat /etc/config/network 

config interface 'loopback'
        option device 'lo'
        option proto 'static'
        option ipaddr '127.0.0.1'
        option netmask '255.0.0.0'

config globals 'globals'
        option ula_prefix 'fd95:d25a:ebd1::/48'

config device
        option name 'br-lan'
        option type 'bridge'
        list ports 'eth0'
        list ports 'eth2'

config interface 'lan'
        option device 'br-lan'
        option proto 'static'
        option netmask '255.255.255.0'
        option ip6assign '60'
        option ipaddr '192.168.50.1'

config interface 'wan'
        option proto 'pppoe'
        option device 'eth1'
        option username '************'
        option password '************'
        option ipv6 'auto'

config interface 'wan6'
        option device 'eth1'
        option proto 'dhcpv6'
        option reqaddress 'try'
        option reqprefix 'auto'
        option auto '0'

Okay I think I found the solution. So apparently it was in the guide in the CLI section. I probed a bit with variables and got it.

Instead of creating an interface alias for wan (@wan) what should be done is an interface for the device that is connected to the modem, in my case eth1. Static IP address can be any address on the same subnet as the modem in my case 192.168.1.* This interface would make that subnet available and now it is possible to reach the ISP's modem at its usual address in my case 192.168.1.1.

Thanks everyone for taking the time to try and assist me.

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