More than one DHCP active at once

abofrapa · May 9

My internet connection is so unstable: it disconnects suddenly every now and then. My fingbox shows this alert DHCP not healthy and that I have more than one DHCP active at once. More than one DHCP active at once, 2: 192.XXX.3.1 (D8:0F:99:C2:64:55) on 192.XXX.3.0/24,192.XXX.10.1 (98:F1:99:B2:2F:D8) on 192.XXX.10.0/24. I've been looking for a solution for some time, and nothing's worked. I use an Apple computer, if this information is vital. Could someone please help me? Thanks in advance, and please stay safe.

DavidF · May 10

Abofrapa,
Can you tell us a bit more about your network? From what you are saying and Fing is reporting it sounds like you have two routers active at the same time, each with its own network (x.x.3.0/24 and x.x.10.0/24). If Fing is seeing both then the networks must overlay each other with would present a host of problems.

DavidF · May 12

Abofrapa,
It sounds like both routers are trying to route for your internet services. If you can I would physically separate them - just allow your telephony devices (phones, SIP devices, etc) to connect to the NTT router. All of your internet devices should connect to the Softbank router. You may want to be clear with both providers (especially NTT) what services they are providing (i.e. billing) to you.
In any event, having both active on your network is bound to cause multiple problems - segregation or consolidation is key to you having reasonable performance.

Good luck!
David

ProTecK · May 29

@abofrapa I have a hunch what is going on, I cant look up anything specific because you are not giving any specific info, like model numbers for those 2 devices, how the devices are interconnected, and what other devices are on your network.
You mentioned one was for your phone service. Exactly what type of service are you using? How is it connected?
I've come across this so many times it may also apply here. This NTT router, does it have 2 ethernet plugs and 1-4 analog phone plugs on it? A device like that would create a 2nd network on the 2nd ethernet plug. The only devices that should be connected to that 2nd plug would be VOIP specific. If you have that 2nd plug connecting back to your other router that is the problem.
I could probably spot the problem if you could give some model numbers and describe what connects to what. Do you know which device provides the wifi? Are your phones VOIP or analog?
We can guess at your problem all day but without this kind of info, it's not even an informed guess. Help me help you.

abofrapa · May 11

Many thanks, David, for the help. Yes, I have two routers provided by the same ISP. The old one is from Softbank ( I'm now resident in Japan ) and the newer one is from NTT, the telephone company. The old one is solely for the Internet, and the new one is for the telephone service they have teamed up with. Until quite recently, I didn't even know they were both routers! Oddly enough, the units seem to have functioned without interrupting my Internet connection until a few months ago. I've made calls to their support desk, but they have not been able to solve the problem: they only changed the router, assuming there was a problem with the unit itself. Thanks again, David.

abofrapa · May 12

David,
Thanks a lot. I'm going to implement the recommendations you've made, and I'll see how it works.

PWTCC · May 23

Okay, before the power bump tonight all was well with FINGBOX. Now I get a notification that there are two DHCP servers on the network. I have double checked all my devices and find no #2. DHCP server? Matter of fact I only have 11 connected devices. INCLUDING FINGBOX. I have a box from a internet survey sight that caused the problem. After rebooting it I found that FING detected no rogue device trying to be a dhcp server. The device in question is supposed to be hidden from the network! So problem was resolved by Myself. Happy the Community was here though! (Background: 26 years Internet NERD/GEEK)

abofrapa · May 23

PWTCC, many thanks for the input. Will keep that in mind as I continue to search for the reason why my Internet connection is unstable.

PWTCC · May 27

Well that worked for about 24 hours. I have that Box messing with the DHCP again. I have reset it twice. Once by power and once by reset button. I'm trying to get in touch with those folks and try to resolve this as it is killing my internet connection.

abofrapa · June 5

Many thanks, ProTecK for the input. I have an NTT RT-500KI which is connected to a SoftBank. The NTT router is for VoIP phone service and the Softbank router is for the Internet. I called Support last week since I couldn't solve the problem. They had me switch off all the devices, remove all the the cables connected to each of the devices, and then reconnect them one by one. Long story short, I now have an Ethernet cable going directly into an older Mac PowerBook, and I'm connected by Wi-Fi on the newer PowerBook. I'm not getting the more than one DHCP alert anymore, but on both computers say, "You have connectivity problems. You have a number of issues to be fixed.Health check code: N40F-N801." This NTT unit has 4 ethernet plugs and two analog phone plugs. One cable goes into the SoftBank router, another into a VDSL unit, and another into the analog phone outlet. And, of course, the Fing unit takes one slot. I don't know if this information is enough to troubleshoot, but I'd appreciate any help. Once again, thank you so much. If you need any more information, I'll provide it. Greetings from Osaka, Japan.

ProTecK · June 5

Ok, I'm having a hard time following your description of what is connected to what and how.
Most documentation I can find is in Japanese. My Japanese only goes as far as the little I have used since my year in Okinawa. Knowing Nagewaza and how to count isn't helping me here. If my Sensai only knew how little I know I never would have seen this Brown Belt.

This VDSL unit is something you didn't mention before? Starting at the handoff. (That sounds like its the VDSL line?)
Hell, The more I try and wrap my head around it the more you have totally lost me.
Let me make a sample below and you can try and fit your network into this way of mapping it.
I am going to list different devices here since I don't know where yours should fit in relation.

FROM the Wall:
Coax Cable > Coax connector [Cable Modem (bridged mode with no routing rules)] LAN ETH Plug> ETH Cable > WAN Port -[Router w/ WiFi]

[Router w/ WiFi] has 4 LAN Ports:
LAN1 > ETH Cable > WAN Port [Voip Router]
LAN2 > ETH Cable > ETH Plug -[Laptop]
LAN3 > ETH Cable > ETH Plug -[Printer]
LAN4 > Unused
WiFi > Any wifi devices

[VOIP Router] has 4 LAN Ports & 2 Analog:
LAN1 > Unused
LAN2 > Unused
LAN3 > Unused
LAN4 > Unused
Analog1 > RJ11 cable > [Analog Phone]
Analog2 > Unused

JCAlexandres · July 8

If you still need the old router running, just disable DHCP on it. You should have only one DHCP server on a network.

More than one DHCP active at once

Best Answers

Answers