Can I serve WAN back to my VDSL Modem after Bridging it?

[RebBlumstein]

I've got a VDSL Modem set to Bridge Mode. (TP-Link TD-W9970 v2)
I've got a Router running OpenWrt. (TP-Link Archer C7 v5)

I use PPPoE on the Router to get WAN/Internet access through the VDSL connection.
(I'm pretty sure this is normal, so far...)

The question is: can I somehow convince the Modem to get WAN access through the OpenWrt device, despite it currently being convinced that it's a Modem?

Another way of putting it: can I make the Modem act as a router and modem at the same time, while still routing all WAN traffic through OpenWrt? Does this second question have a different answer?

[yitida]

if you look at this configuration the modem (td-w8970) is bridged and is also a lan client of the router (r7800) so it has internet connectivity (you should add gateway and dns). hope it helps a bit

Vlan newbie advice

hi all! i have a TD-W8970 and a R7800 both with 19.07.2. configured the 8970 as a bridged modem and the 7800 to do routing/wifi/dhcp/sqm and all the good stuff. all is working good. now i'd like to use a single cable from one to the other to use both wan an lan and free some ports, since i've read a lot but no sure, can you guys check this configuration?? i don't use vlan 1, vlan 2 is wan and vlan 3 is lan. is this correct to keep wan an lan traffic separated? or i'm messing up things? 8970: …

cheers

[RebBlumstein]

Did they have to have OpenWrt on the modem too, or am I misunderstanding the config?

[yitida]

yes both device with openwrt. dont know if it is possible with tp-link stock firmware. sorry if i miss understud yor quedtion.

[RebBlumstein]

I don't see TP-Link TD-W9970 v2 in the list of supported hardware. Is it dangerous to try flashing it?

[Kherby]

Sorry to ask but why would you need WAN/internet access with your bridged modem?
I'm running a bridged modem myself and it does have openwrt under the hood. With my mode I do have the option to download diffrent xdsl drivers via internet access and all I need to do for this is to add the DNS and Gateway IP of my Interface that I've added to my main OpenWrt router in order to gain access to the modem over my private LAN.
The thing is that I do have root access to my modem and it does have OpenWrt under the hood + a modified stock GUI. I'm not sure if I would be able to do this with the stock GUI and without root access.

Example modem network config:

config interface 'lan'
	option type 'bridge'
	option proto 'static'
	option ipaddr '10.0.0.1'
	option netmask '255.255.255.0'
	option ip6assign '64'
	option force_link '0'
	option ipv6 '0'
	list ifname 'eth0'
	list ifname 'eth1'
	list ifname 'eth2'
	list ifname 'eth3'
	list ifname 'ptm0.101'
	option gateway '10.0.0.2'
	option dns '10.0.0.2'

Example config on my main Router:

config interface 'modem'
	option proto 'static'
	option ipaddr '10.0.0.2'
	option netmask '255.255.255.0'
	option ifname 'eth1.2'

So if you have the option to add a DNS and Gateway IP to the LAN interface of your modem you should be able to access the internet.

[RebBlumstein]

Thanks for the info! I guess I don't really need it. I'm not sure why it'd ever be necessary in my situation, but I guess I just wanted to know if it was possible.

[Kherby]

It's possible but your modem has to have to the option to set a gateway and dns IP to its LAN interface when in bridge mode but in your case I don't think that you need it. I think the most important part with bridged modems is that you have the ability to access to them via your private LAN on your main router to read out line statistics (syncspeed, errror statitstic aso) and you can easily do this OpenWrt.

If you haven't done this already I would highly recommend to do it. It saved me a lot of time when debugging my VDSL connection in the past.