Router DHCP failing on me?

WJA96 · 16 Aug 2019 at 07:50

It’s a strange one!

As I understand it, the process is that the client (PC, TV) fires off a DHCP request and any available DHCP server will respond. There’s then a bit of quick to-ing and fro-ing while they check the proffered IP address isn’t in use elsewhere on the network. In the event that the Windows PC can’t find a DHCP server, it becomes a DHCP server and gives out 169.254.x.x IP addresses to any other device that will listen. You say that you can see the Netgear allocating IP addresses but clearly the Windows PC isn’t getting an IP address, so it’s not.

WJA96 · 16 Aug 2019 at 08:04

What is your DHCP lease time set to? Long or short? You could just make it VERY long.

.Griff. · 16 Aug 2019 at 12:35

The more I read the more I see references to inherent issues with DHCP on the D7000. Not to mention a user on here with the same issue on the same router.

WJA96 said:
What is your DHCP lease time set to? Long or short? You could just make it VERY long.

You cannot amend the lease period on the D7000 unfortunately. No idea what the predefined lease is but I've seen references to as little as 15 minutes.

WJA96 said:
You say that you can see the Netgear allocating IP addresses but clearly the Windows PC isn’t getting an IP address, so it’s not.

The Windows PC is getting an IP address. At least initially but more on that below.

What appears to happen is this -

Wake up > Switch the device in question on > DHCP on D7000 correctly assigns IP > work away as normal for a few hours > lose internet connection > check assigned IP and it's changed from 192.168.0.x to 169.254.x.x

If the reference I've seen to the D7000 having a lease period of 15 minutes is correct I assume the following is happening;

Device gets IP assigned correctly when turned on > once 50% of the lease period has passed the device requests to extend it but gets no reply from DHCP server > tries again after 75% expired but gets no answer > tries again after 87.5% expired but gets no answer > lease expires and device in question broadcasts for another IP from any DHCP server and gets 169.254.x.x assigned instead.

Quartz · 16 Aug 2019 at 16:59

You only set the lease to such a short time when you're changing DHCP servers. Set it to a week or a month.

.Griff. · 16 Aug 2019 at 17:03

Quartz said:
You only set the lease to such a short time when you're changing DHCP servers. Set it to a week or a month.

I think you've misread my comments.

Namely, I stated there is no ability to set/change/alter/amend the lease period on the D7000.

Stephanie Peterson · 16 Aug 2019 at 17:27

Setup pihole to be dhcp server and see if the problem continues.

Quartz · 16 Aug 2019 at 19:07

.Griff. said:
Namely, I stated there is no ability to set/change/alter/amend the lease period on the D7000.

Ah, I'd missed that. Sorry. Anyway, I thought the default lease time on the D7000 was 1 hour.

.Griff. · 16 Aug 2019 at 20:01

Quartz said:
Ah, I'd missed that. Sorry. Anyway, I thought the default lease time on the D7000 was 1 hour.

You might be right mate. Either way, it seems like multiple devices are requesting lease extensions and are not being acknowledged leading to them broadcasting for another DHCP server and the ensuing issue.

esK` · 16 Aug 2019 at 21:37

I have a D7000 v2 and after a year I just went back to ISP supplied stuff. It kept dropping connections exactly like yours and after the first month of ownership Netgear weren't interested in helping. I did get a replacement but that was as bad as the first one I brought.

.Griff. · 17 Aug 2019 at 16:53

esK` said:
I have a D7000 v2 and after a year I just went back to ISP supplied stuff. It kept dropping connections exactly like yours and after the first month of ownership Netgear weren't interested in helping. I did get a replacement but that was as bad as the first one I brought.

That makes three of us in this thread with same router and same issue. It can’t be a coincidence. Maybe I’ll look for a replacement.