New modem won't connect with OpenWrt router

Installing and Using OpenWrt
1

I've been using OpenWrt on a Netgear WNDR3800 router for about 5 years. During that time I've replaced my ADSL modems several times without encountering any problems. Router WAN is set as DHCP client. Connect the WAN on the router to a LAN port on the modem and it all works.

Until a few days ago when I changed my ISP, who provided me with a new modem, which won't connect with the router. The new modem is a (Telstra) Arcadyan LH1000.

All my other devices connect to the modem LAN OK, and the router will still connect to the old modem, so there doesn't seem to be a physical problem. The new modem is set to the same fixed IP address (192.168.1.1) as the previous one.

Any ideas on how I might go about tracking this down? I'd really like to identify the cause rather than just bypassing it.

Jomlo

2

probably somethink link-negotiation related... try to install ethtool ( extroot may be required )...

and see what your end ( and if the telstra displays it maybe with a laptop connected... it's end ) is showing...

a spare switch in the middle may also show something...

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3

Additionally make sure that WAN- (the modem) and LAN subnets don't overlap, considering that OpenWrt's default LAN IP would be 192.168.1.1 as well (one or both need to be changed).

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4

.... or convert the openwrt device to a dumb AP.

https://openwrt.org/docs/guide-user/network/wifi/dumbap

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5

They don't overlap. My setup has been working successfully for years, only the ADSL modem id different. Why it is behaving differently to every other modem I have used is what I am unable to discover.

6

A dumb AP wouldn't suit my purpose.

7

The only difference is no extra firewall.

Unless you need two subnets.

8

Exactly. I need two subnets.
In any case, I want to identify the reason for the problem, not just bypass it.