Printer not getting IPv4, suspect IPv6


there's a printer (Brother MFC-L2700DW) that I had running in my home wifi. Then I set up IPv6 as well. Now the printer is not getting an IPv4 via DHCP. Well, it now has some default IP after a timeout. Statically setting the printer's IP doesn't work either.

In LUCI I can see its MAC address in the wireless menu (under "Associated Stations"). Apparently it also has a link-local (fe80:...) IPv6 but no IPv4 or any other address.

At least I suspect that IPv6 is causing some trouble on the printers side, since I can't remember touching anything else.
On the other hand: I disabled IPv6 on the LAN interface again and it's still not working. (Is it enough to disable "IPv6 assignment length" :thinking:)
I also disabled the 5 GHz wifi because I read somewhere that Brother printers had some trouble with these too. That didn't help either.

Do you have any ideas how to debug this or did you have a similar issue?
Thanks in advance!

your best bet is to make sure ipv6 is enabled on the printer, then just use the IPV6 capabilities. If it has a bug see if there are firmware updates.

shows how to ensure ipv6 is enabled on their printers. Does this show enabled?

I can't access the printer via browser since it's not getting an IP, but I enabled IPv6 on the printer itself. No luck.

Good point on the firmware, though. Of course the firmware updater is available for Windows only... Now I need to find a way to update it using linux.

Can you have the printer print its network config page? Perhaps it's getting a ULA?

It automatically printed such a page when it connected. No IPs on that page. Only SSID, channel, MAC, authentication mode etc.
Maybe I'll try a direct connection to my laptop.

it's connecting via wifi? and what device is the router/access point?

Yes there is no wire available. The router is a Linksys WRT1200AC running OpenWRT OpenWrt 19.07.8.

I've had nothing but trouble with WRT devices with mvebu drivers when it comes to this kind of thing. They seem to have problems delivering multicast and broadcast packets particularly to devices that use sleep mode, so printers, phones, etc.

You might run Brother Utilities and select Tools > Network Connection Repair Tool.

My MFC-L3770CDW had a default IPv4 IP of out of the box.

Ive had many wireless brother printers since the wireless G days and have found them to be amazingly reliable, and yes brother printers even new ones typically do not use 5g at all. However that's normal for most occasional use devices. They do this on purpose because 2.4G has much longer range and less issues with brick walls and such. That and printers sit idle 99% of the time so they don't use much bandwidth.
Wish I could help you more then that, good luck. If you figure it out please report back.

I just realized that I can't connect to the wifi with my laptop as well (Didn't realize it since I have it in a docking station most of the time). So it's not just the printer.

Then I double-checked my wifi settings in LUCI: my guest wifi is connected to my guest lan. But my regular wifi is not connected to anything. Even stranger: If I select my lan network, it doesn't save the setting and reverts to 'unspecified'.
And to top it all off, I have some android devices that refuse to properly connect to my guest wifi but DO work with my regular wifi :thinking:

In my system log I'm also seeing lot's of messages like this: daemon.warn dnsmasq-dhcp[3876]: DHCP packet received on wlan1 which has no address.

So I edited /etc/config/wireless using ssh and added the missing option network 'lan' to the appropriate interfaces. (Does anybody have an idea why it was not selectable in LUCI?)

However, only after disabling the 5 GHz interface, I could properly connect again.