Upgraded WRT1900ACv1 from CC 15.01 to lede-17.01.4-mvebu-linksys-wrt1900ac-squashfs-sysupgrade.bin

I've installed lede-17.01.4-mvebu-linksys-wrt1900ac-squashfs-sysupgrade.bin onto my Linksys WRT1900ACv1 three times now, each time the WAN interface DHCP client does not seem to connect to my ISP properly.

With CC 15.05.1, the WAN interface was eth1 connected to my Zoom cable modem with Time Warner/Spectrum as my ISP:

Type: dhcp
Address: 24.55.57.115
Netmask: 255.255.224.0
Gateway: 24.55.32.1
DNS 1: 209.18.47.61
DNS 2: 209.18.47.62
DNS 3: 209.18.47.63
Connected: 0h 43m 11s

But when I boot into LEDE-17.01.4, the WAN interface eth1, configured to use DHCP, does not seem to be able to connect fully, i.e.: it never gets an IPv4 address.

I've taken a look at the system logs and can't see anything that shows an obvious problem, so how would I troubleshoot this further?

Thank you for your help!

Contact your ISP to unbind MAC address

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How did you go with this? I'm having similar issue with my internet connection. Its VDSL2, is supposed to be auto IP and auto DNS, no tagging etc.
If anyone can help me to connect I would be very greatful. I've lost a lot of my hair trying to fiddle with this. Unfortunately I really dont have a strong grasp of how to set it up.
I'm using Aussie Broadband. WRT1900acsv2.

I am bumping this for the sake of finally finding the solution. My ISP (Spectrum, Time Warner in the US) will only give a DHCP lease during a short window after the modem is reset (probably 2 minutes or less).

This meant every time I diagnosed with my desktop plugged directly via ethernet into a newly powered modem, I would get a DHCP lease and connect to the internet successfully. However, I could not move the ethernet cable from my desktop to my router and have it get the same or a new DHCP lease. Instead, I would have to repower both the modem and router when connected by ethernet for the first time.

These two references helped:

  1. Can OpenWrt 19.07.3 Router be used with Spectrum Cable modem?
  2. https://www.reddit.com/r/openwrt/comments/m08su9/faliure_in_openwrt_in_configure_spectrum_network/

Tech support from Spectrum wouldn't help me because it wasn't their equipment for the modem or router. Tech support for the modem couldn't help because they didn't know OpenWRT. Only the Internet helped!

I don't use Spectrum/TWC, so I cannot speak with certainty on the nuances of their system... but I do use Comcast and I don't believe that the DHCP lease time is limited like this on Comcast and possibly US based cable ISPs in general.

AFAIK, this is common across most cable ISPs. The issue is not time, but rather MAC address learning/binding. The cable modem will learn the MAC address of the device that is immediately connected, and will only issue DHCP leases to that singular device. The cable modem must be power cycled (sometimes several times) to clear that binding such that it can learn a new MAC.

Moreover, the DCHP lease, and the IP issued, is often a function of the actual MAC address, meaning that you cannot have two different devices (with different MAC addresses) and expect them to get the same IP address from the ISP. In fact, dnsmasq (a common DHCP/DNS server, and the one that OpenWrt uses by default) does exactly this -- the IP address issued by DHCP is determined by an algorithm that uses a hash of the MAC address to determine the specific address (you can disable this and tell dnsmasq to issue sequential IPs).

Why flashing such old builds? OpenWrt 15 and lede 17 are verry outdated now. you should be flashing openwrt-21.02 or the new RC of OpenWrt v22.03.0 RC6 is building now.

This appears to be a thread that was revived so that the OP could describe the solution they found (at least with respect to the ISP connectivity). The first post was in June 2018, so LEDE 17.01 would have been current (18.06.0 was released in July).

Correct @psherman! I was describing the resolution for the root cause of my issue: my ISP DHCP lease window.

@tapper I'm on WRT32X hardware and OpenWRT 21.02.3 now and retired the older hardware that I had updated as far as I could.

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