Posted: Sat Apr 03, 2021 4:18 Post subject: Not obtaining LAN IP addresses, bug or coincidence?
Not obtaining LAN IP addresses, bug or coincidence?
- I connect various laptops of different ages to a LAN port of a router.
- WAN port is not in use, the router is set up to be a WiFi client (in a router mode, not a bridge).
- I prefer DD-WRT, especially when I deal with older routers, so I flash the router with the most recent DD-DRT firmware available for that model.
- I do not change any settings except time zone, "keep alive" and making it a WiFi client.
- I noticed that some laptops do not obtain IP address when connected to the LAN ports.
- I tried different cables, tried different ports - nothing works with some laptops (wireless is ok).
- The LED lights on both the laptops and the router(s) are on or blinking.
- It does work occasionally with some other laptops. I have not discovered a pattern (yet).
- So I thought ok, must be a faulty old router. Flashed DD-WRT on another one. A different brand, different model, maybe a few years difference between the routers. SAME! Some laptops do not obtain IP address from any of the LAN ports.
- Those routers have never been known to have any problems with LAN ports until their original firmware was changed to DD-WRT.
- The laptops were not known to be unable to connect to LAN with Ethernet cables elsewhere.
- I am on the router number 4! So 4 routers in a row have the same issue! Too much for a coincidence? Anybody noticed a similar issue?
I don't want to blame DD-WRT without a proof. After all, it is possible that all 4 routers have faulty LAN ports (all ports though?). But it manifested itself only after changing to DD-WRT in each of the routers. All these routers had wired devices connected to them previously with no problems. It is just too much for a coincidence, wouldn't you think?
I just thought to check if it is a common problem and other people ran into it. Then I would just know that it is not me going crazy and maybe there is something going on that is common.
What is the right forum for this? I am not asking for any technical support and i don't have a question about configuration.
I tried the following routers:
- NETGEAR N750 WNDR4000 (DD-WRT as recent as a couple of months old)
- Linksys E1200 (DD-WRT as recent as a few weeks old)
- TP-Link TL-WR740N (r.40559, fails newer updates)
- the fourth one (was the first one) i already recycled, sorry.
Sorry I did not power up the first three to give you exact firmware. I can if it makes a big difference, but i tried it fairly recently (comparing to speed of firmware releases) and I think i have the most recent ones.
Joined: 08 May 2018 Posts: 14207 Location: Texas, USA
Posted: Sat Apr 03, 2021 14:35 Post subject:
And your Winblows clients not getting an IP address is a Winblows issue. Do not configure large frames on the interfaces, and if you absolutely have to, reset networking completely to wipe out all of the crap in the registry. Or, you could just use the native troubleshooter and it will reset the interface and obtain an IP automagically, unless something is really bunked.
The defaults configuration out of the box shouldn't be the problem, unless you mucked up the configurations somehow in DD-WRT. Keep in mind, all routers listed possibly have issues with LAN ports, so look that up....
The TP-Link will have to be upgraded via magic CLI voodoo, possibly over serial. There is plenty of discussion on that. 40559 was a sh*t build and prior to upgrading normally being completely fixed.
