Router DHCP failing on me?

.Griff.

.Griff.

.Griff.

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I have a Netgear Nighthawk D7000 that I've used for a year or two with no issue.

As I have multiple devices on my LAN at any one time I use the internal DHCP server to assign devices on the LAN IP address automatically in the 192.168.0.2 - .254 range.

Nothing earth-shattering there.

However, of late, I've noticed that more than one device has lost internet connection and when I've triaged the issue the device has been assigned a 169 address. This has happened to my main PC as well as a Samsung Q9FN.

Any obvious reasons why this would happen lately? I've had two (ish) years of no issues and then this is happening more and more often of late. No firmware upgrades on the D700 either.

DHCP server failing on me?
 
How often does this occur?

What's your current network topology? How do both devices exhibiting issues connect? Is it via the same switch or completely different runs?
 
Hyburnate said:
How often does this occur?

What's your current network topology? How do both devices exhibiting issues connect? Is it via the same switch or completely different runs?
Click to expand...

Once a week may be that I'm aware of. I've been away on a course last week so haven't been here to have much visibility but it did it again yesterday afternoon.

Symptoms differ for each device (due to the nature of the device itself) but on the Windows PC websites will fail to load suddenly and IPconfig shows a 169 address assigned to the PC. On the Q9FN Youtube videos will stop and constantly attempt to buffer. Going into Network settings will show a 169 address assigned to it.

PC is connected directly to the D7000 via ethernet, the Q9FN does go via a Netgear switch (used for AV devices).

Rebooting the router fixes the issue each time.

Quartz said:
Have you checked the cable? No cuts, no kinks, securely plugged in both ends? Check especially where the cable goes through a doorway.
Click to expand...

Admittedly I haven't. I probably should as we have two cats and I wouldn't put it past them chewing on stuff they shouldn't. I'll do that tonight.
 
Had the same sort of issue with an old HomeHub router. Never got to the bottom of it, got Virgin installed. Maybe router hardware just degrades? I mean it's passively cooled and on 24/7. The HH seemed very warm all the time.

The VM Superhub has it's own issues, usually WFi, but so far the ethernet/DHCP is working fine.
 
If you want to dig in at a technical level, install Wireshark on your PC and start a trace to watch the DORA process (Discover, Offer, Request, Acknowledge) that makes up DHCP.

Start the trace and then run ipconfig /renew from a command line to see what happens. To filter the Wireshark display, type "bootp" into the filter box (DHCP is a feature of BOOTP)
 
#Chri5# said:
If you want to dig in at a technical level, install Wireshark on your PC and start a trace to watch the DORA process (Discover, Offer, Request, Acknowledge) that makes up DHCP.

Start the trace and then run ipconfig /renew from a command line to see what happens. To filter the Wireshark display, type "bootp" into the filter box (DHCP is a feature of BOOTP)
Click to expand...

Good suggestion. The course I alluded to was on OSINT and we covered DORA as part of that. I'll give it a go.
 
.Griff. said:
Once a week may be that I'm aware of. I've been away on a course last week so haven't been here to have much visibility but it did it again yesterday afternoon.

Symptoms differ for each device (due to the nature of the device itself) but on the Windows PC websites will fail to load suddenly and IPconfig shows a 169 address assigned to the PC. On the Q9FN Youtube videos will stop and constantly attempt to buffer. Going into Network settings will show a 169 address assigned to it.

PC is connected directly to the D7000 via ethernet, the Q9FN does go via a Netgear switch (used for AV devices).

Rebooting the router fixes the issue each time.



Admittedly I haven't. I probably should as we have two cats and I wouldn't put it past them chewing on stuff they shouldn't. I'll do that tonight.
Click to expand...
Doesn't sound like a single cable fault then, as both devices are having issues yet are connected differently. For this sort of thing, I'd expect more of a kink in the cable rather than a break.

I echo what Chris says regarding Wireshark but it'll be pointless, you'd need to run it for circa 7 days until the issue happens and whilst it would likely point you in the right direction, in a home environment there's a simpler fix.

Give your devices static IP addresses, make your DHCP scope smaller, and set devices to have their own Static (just your PC and TV for now).
 
Hyburnate said:
Give your devices static IP addresses, make your DHCP scope smaller, and set devices to have their own Static (just your PC and TV for now).
Click to expand...

Cheers. I'd considered doing just that but reluctantly held off until now as there's circa 15 devices on the LAN (most wireless) and I'd only seen the symptoms exhibited on the two devices I use daily - PC and TV.

I might just do what you suggest and assign static IP to the two devices I use most often.
 
.Griff. said:
Cheers. I'd considered doing just that but reluctantly held off until now as there's circa 15 devices on the LAN (most wireless) and I'd only seen the symptoms exhibited on the two devices I use daily - PC and TV.

I might just do what you suggest and assign static IP to the two devices I use most often.
Click to expand...

Honestly, it sounds like packet loss, it's a nice and simple fix if that's the only issue you're experiencing. If it was a commercial environment definitely Wireshark etc but in this environment, you'll get away with cheating sightly.
 
Dunno if it helps but my D7000 started doing the exact same thing after 2 years of ownership. It mainly affected wireless. I tried everything I could, firmware, beta firmware, moving router, new cables etc. in the end I had to replace the router and as soon as I got a new one, no issues.
 
VaderDSL said:
Dunno if it helps but my D7000 started doing the exact same thing after 2 years of ownership. It mainly affected wireless. I tried everything I could, firmware, beta firmware, moving router, new cables etc. in the end I had to replace the router and as soon as I got a new one, no issues.
Click to expand...

That's interesting then. Same router and same time period.

Now you mention it I've had periodic issues with my iPad (over wireless obviously) and I just ended up resetting the networking settings on it. Maybe it's the same issue as experienced with the PC and TV.
 
Have you recently added or reset any devices on the network that might have a DHCP server on them?

The 169.254.x.x/16 address range is an old IBM standard called APIPA and it’s what your devices get handed out when there is no DHCP server running.

Just because they are connecting over the WLAN doesn’t mean they are getting an IP address from the router. If, for some reason, the Netgear thinks it’s not the DHCP server for the network, it won’t give out any IP addresses and it (or something else on the network) will instead hand out APIPA addresses. Can you check if the DHCP server on the Netgear is running? Port 67 is the one to check. If it’s not, that’s why it’s handing out APIPA addresses. If it is, then something else is handing out APIPA addresses. That could be a wireless extender, a NAS unit or even the Virgin Hub if it’s suddenly come alive.
 
You got any static address on the lan in the same range as the dhcp pool? Sounds like an ip conflict to be honest. WIndows doesnt always pop up a wee moan about it either, first you know is when devices stop working and fire up a gash 169 address.
Maybe move your dhcp range to another subnet if you want to nail it down.
 
Stephanie Peterson said:
You got any static address on the lan in the same range as the dhcp pool? Sounds like an ip conflict to be honest. WIndows doesnt always pop up a wee moan about it either, first you know is when devices stop working and fire up a gash 169 address.
Maybe move your dhcp range to another subnet if you want to nail it down.
Click to expand...

No statics in use.

WJA96 said:
Have you recently added or reset any devices on the network that might have a DHCP server on them?

The 169.254.x.x/16 address range is an old IBM standard called APIPA and it’s what your devices get handed out when there is no DHCP server running.

Just because they are connecting over the WLAN doesn’t mean they are getting an IP address from the router. If, for some reason, the Netgear thinks it’s not the DHCP server for the network, it won’t give out any IP addresses and it (or something else on the network) will instead hand out APIPA addresses. Can you check if the DHCP server on the Netgear is running? Port 67 is the one to check. If it’s not, that’s why it’s handing out APIPA addresses. If it is, then something else is handing out APIPA addresses. That could be a wireless extender, a NAS unit or even the Virgin Hub if it’s suddenly come alive.
Click to expand...

Nothing has been added and/or reset lately. Certainly, nothing that has a DHCP server on them.

The DHCP server is definitely running on the D7000. I'm working from home and I can see it assigning IP's to the work laptop and mobile correctly.

As for something else handing out IP addresses, there is nothing on the network that might do that. No NAS, not sure where the reference to the Virgin hub came from as I''m not, and never have been, with Virgin. Yes there are a couple of wifi extenders but this IP issue is affecting wired devices.
 
bremen1874 said:
Any Powerline adapters. It's quite possible for them to connect to a neighbour's network and give you access to their DHCP server as well as your own.
Click to expand...

No powerline adapters.

The two (that I've noticed) devices affected are wired directly to the D7000 (well the Q9FN does go via a switch but certainly no powerline adapters or wife extenders being used for these devices)
 
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