One wireless interface connecting and then not assigning DHCP addresses

Installing and Using OpenWrt Network and Wireless Configuration
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NOTE: The marked solution links to a GH issue that describes the problem and solution in detail; see my post below it for the 10,000 ft overview. The secret is to switch to B/G only (ie no "N").

Hey guys, long time listener, first time caller. I'm running OpenWRT 18.06.1 on a WRT3200ACM which has four antennae and three Atheros wireless interfaces: one nac, one bgn, and one bgnac. The latter is a bit weird and frequently has issues with all firmware, but that's another issue for another day. Right now I'm trying to connect some 2.4GHz devices to the second interface. Everything connects but only computers ever get addresses.

When I connect a computer, I see this in the syslog:

Mon Jan  7 03:57:46 2019 daemon.info hostapd: wlan1: STA 68:ec:c5:f5:37:0f IEEE 802.11: associated (aid 2)
Mon Jan  7 03:57:46 2019 daemon.notice hostapd: wlan1: AP-STA-CONNECTED 68:ec:c5:f5:37:0f
Mon Jan  7 03:57:46 2019 daemon.info hostapd: wlan1: STA 68:ec:c5:f5:37:0f WPA: pairwise key handshake completed (RSN)
Mon Jan  7 03:57:48 2019 daemon.info hostapd: wlan1: STA 68:ec:c5:f5:37:0f IEEE 802.11: authenticated
Mon Jan  7 03:57:48 2019 daemon.info hostapd: wlan1: STA 68:ec:c5:f5:37:0f IEEE 802.11: authenticated
Mon Jan  7 03:57:52 2019 daemon.info dnsmasq-dhcp[6663]: DHCPDISCOVER(br-lights) 68:ec:c5:f5:37:0f
Mon Jan  7 03:57:52 2019 daemon.info dnsmasq-dhcp[6663]: DHCPOFFER(br-lights) 192.168.2.194 68:ec:c5:f5:37:0f
Mon Jan  7 03:57:54 2019 daemon.info dnsmasq-dhcp[6663]: DHCPDISCOVER(br-lights) 68:ec:c5:f5:37:0f
Mon Jan  7 03:57:54 2019 daemon.info dnsmasq-dhcp[6663]: DHCPOFFER(br-lights) 192.168.2.194 68:ec:c5:f5:37:0f

This is what I see for any other device, although this is from my Pixel 2:

Mon Jan  7 03:57:26 2019 daemon.info hostapd: wlan1: STA 40:4e:36:d2:be:30 IEEE 802.11: associated (aid 1)
Mon Jan  7 03:57:26 2019 daemon.notice hostapd: wlan1: AP-STA-CONNECTED 40:4e:36:d2:be:30
Mon Jan  7 03:57:26 2019 daemon.info hostapd: wlan1: STA 40:4e:36:d2:be:30 WPA: pairwise key handshake completed (RSN)
Mon Jan  7 03:57:36 2019 daemon.info hostapd: wlan1: STA 40:4e:36:d2:be:30 IEEE 802.11: authenticated
...
Mon Jan  7 03:58:02 2019 kern.debug kernel: [ 2430.421936] ieee80211 phy1: staid 1 deleted

This only happens on the 2.4GHz bgn interface, and LuCI shows the device to be connected with a ? for the host field. I've tried this:

  • With a fresh flash, the only change being enabling the wireless network
  • With this interface on its own network
  • With this network as a 2.4GHz equivalent of the network running on nac

And I get the same result regardless of what I do. I've tried restarting dnsmasq and restarting the network; I'm not sure what else to do. How can I get wlan1 to hand out DHCP addresses so my 2.4GHz only devices can work?

Things that work:

  • 2017 MBP
  • 2017 HP laptop with Intel dual band wifi

Things that don't:

  • Pixel 2
  • Nest
  • LIFX lights
  • Chromecast and Audio
  • Echo Dot

TIA

2

It sounds like you may have a bridge set up for your 5 GHz radio, but not your 2.4 GHz radio. Do you have wlan1 bridged to a network interface or VLAN? If so, is DHCP enabled for that network?

Fallback debugging would be to run tcpdump (tcpdump-mini is sufficient) on the network to see what is going on with the DHCP process. From memory,

tcpdump -ni <ethN> udp portrange 67-68
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I guess this is a known issue with the wifi drivers for this device: https://github.com/kaloz/mwlwifi/issues/278

2 Likes
4

omg @eduperez thank you so much for posting that! I actually looked through the mwlwifi source code to find an error I was getting initially configuring the interface, but never thought to look there for this error.

SOLUTION
Until the above linked issue with mwlwifi is closed, you must use wlan1 on your WRT3200ACM (likely other routers as well) in Legacy (B/G) mode. If you are having this problem, try switching your interface to only serve B/G and see if it fixes it; if it does, you have the mwlwifi problem.

1 Like
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Glad to know you found a solution! I am currently using the third radio on the router for my IoT devices.

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