R7800 Showing Multiple DHCP Lease Events at Renewal

[blunderdome]

Since picking up a new R7800 a couple of weeks ago I've noticed something odd in the event logs.  It seems that when devices check in for DHCP renewal the logs will sometimes show the same device being issued an IP multiple times over the course of 30 seconds or more.  This happens with both wired and wireless clients and seems to be somewhat random.  On one occasion now it actually caused a connection drop on a wireless device.  I'm running the latest firmware and have tried factory resets/reapplying the firmware a couple of times and the behavior persists.

Setting devices up with static IPs obviously remedies the behavior but that's not something I want to be doing for tablets/phones/laptops.

On my R7000 this behavior doesn't occur.  I'm still within my 30 day window to swap out this device so if this behavior is unusual for the R7800 I'd like to know so I can return it.  Can anyone comment on whether or not they see similar behavior with their R7800's?

Pic attached illustrating the issue:

[blunderdome · Accepted solution]

Yeah, I picked up a second one over the weekend to try out - it did the same thing almost immediately so I'm not going to stress it.  Gave the devices that were finicky static IPs and called it a day.

[GearNetRouter]

Remove the specific device and try it on another router?

[blunderdome]

Like I said, it doesn't happen on other routers and it's not happening to one specific device.

[doraemon]

Perhaps, use a different fw version?

If it persists, replace the unit.

[blunderdome · Accepted solution]

Yeah, I picked up a second one over the weekend to try out - it did the same thing almost immediately so I'm not going to stress it.  Gave the devices that were finicky static IPs and called it a day.

[mondenath]

You can also try sending the log not on full but say 1hours schedule. It will not be full log. But you may need to add it to labels like in gmail to avoid 24mails a day and more to come in a month. Say 750+ a month

[TheEther]

TL;DR Those DHCP logs are not necessarily address lease renewals; the device could be requesting other information.  The router will log any request.  Just ignore them.

Many people think of DHCP as just the protocol for handling dynamic IP addresses, but it can do so much more than that.  Look at all of the options that can be included in a DHCP packet.  The common options are IP address, subnet mask, default gateway and DNS servers.  Some devices can and will send DHCP packets to the DHCP server to request other information besides these common options.  If you are curious, you can run Wireshark to see exactly the device is asking for.  The DHCP server in the router will not necessarily be able to handle these other options, but it will respond with whatever information it can provide.   On Netgear routers, this will always appear in the logs as a DHCP message.

Additionally, DHCP is a device-driven protocol.  The device always initiates the request.  The router is passive.  Despite any differences in the frequency of DHCP messages observed between a R7000 and a R7800, it's not due to the routers.

It can be a nuisance to see so many DHCP messages in the logs but you can ignore them.  It's very unlikely that the connection drop on a wireless device was caused by them.  More likely, the wireless device lost its connection because it was too far away or the signal was otherwise disrupted.  Once the device re-established the connection, it immediately asked for a dynamic IP address.