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Forum Discussion
rdouma
May 30, 2024Guide
Orbi RBR850 unstable/DHCP assignment issues after reboot
Post concerns a RBR850 and 2 RBS850 satellites, all running firmware version V7.2.6.31_5.0.24. Summary: I have to turn off all WiFi devices near the router in order to get a successful reboot whe...
rdouma
Jun 02, 2024Guide
I was excited to read that, for you, not making any DHCP reservations resolved the problem.
Eh... where did I say that? I surely didn't intend to say that; one of the steps I used to get back to a workable solution was the opposite of that: I basically have all known devices in my house as a named device now.
Some time after I first saw this I tried my RBK50 kit and saw the same problem leading me to think it is related to some sort of a race in the DHCP server when the number of devices is large, possibly more than about 50 but more than 80 is when I really started having a problem.
Very well possible it's related to the amount of devices. I have a bunch of them and a large amount was added over the last months when installing Wiz light bulbs.
This has been a problem for years and Netgear not paying any attention to the forums is just not good enough, but then they give only three months support on new purchases, so ...
Yeah, with you on that one. I would expect that you would never want to restrict users to be able to easily submit bug reports but no. Luckily there's this forum and some power users here that seem to know their way around this but in my opinion NetGear should be welcoming bug reports instead of trying to make it hard to submit one.
raven_au
Jun 03, 2024Virtuoso
rdouma wrote:
I was excited to read that, for you, not making any DHCP reservations resolved the problem.
Eh... where did I say that? I surely didn't intend to say that; one of the steps I used to get back to a workable solution was the opposite of that: I basically have all known devices in my house as a named device now.
Umm ... reading your post again I think I misunderstood, sorry.
Nevertheless, the dhcp server is probably single threaded and applications like this usually spawn a sub-process for each request to increase throughput. So doing that means they need to record information about the address assignments in a file somewhere because sub-processes are themselves isolated from one another. If there are multiple concurrent requests (a lot of devices wanting to register at once) and the locking of that file isn't right or isn't even done then you can easily get corruption in the file.
I've seen that before in Linux, for years we had a lot of trouble with /etc/mtab (mounted mounts list), in spite of quite a sophisticated locking algorithm it frequently got corrupted during heavy mount activity. It wasn't until /etc/mtab was made a symbolic to the proc file system mount table it was resolved (the proc file system mount tables are files generated on the fly from kernel data structure, they are not written to).
So, it is easily possible the dhcp server is broken, of course the problem is that Netgear hasn't done anything about it or aren't competent enough to fix it if they have tried. The problem is no secret either, there have been a number of reports of it over the years.
For my part I have never been in a position to log a call with support because of the support policy and even if I was within the twelve weeks period at some time I'm not at all sure I would be willing to subject myself to the pain and suffering of what logging a support call involves.
Ian
- rdoumaJun 07, 2024Guide
Sorry for my late response. I agree it looks suspiciously like a the DHCP server not being thread safe. I'm going to experiment with running a docker with a DHCP server and see how a network restart behaves with that.
- TimtechJun 09, 2024Apprentice
Any chance you have a MyQ garage door opener? I moved mine to the guest network and dhcp is working well ever since.
- rdoumaJun 11, 2024Guide
Well, I can definitely confirm this is the problem. I have spent countless hours trying to figure out what the issue was, attributing it to network interference but no. I am now running ISC DHCP on Ubuntu and DHCP works flawlessly. Quite unbelievable if I'm being honest that such a core feature of the router is clearly broken. I'll log an issue with NetGear.
- geh4Aug 09, 2025Tutor
Did netgear resolve this issue? I have the same issue (many wifi devices and dhcp cannot assign addresses after power outages). I can also confirm that turning off wifi devices, resetting the orbi and then slowly turning the wifi devices back on can resolve the issue.