DHCP not working correctly
DHCP not working correctly
DHCP not working correctly
2019-04-17 01:17:52 - last edited 2019-04-18 01:24:47
Model: Archer A7
Hardware Version: V2
Firmware Version: 1.1.1 Build 20190115 rel.60612(5553)

First of all, my router is an Archer A6 (not A7) but such model is not in the dropdown list.

The router works fine, except for one major problem: when a wi-fi client connects the DHCP will occasionally serve an address on the 192.168.2.x range instead of the expected 192.168.0.x range. That happens randomly. When the problem happens, the wi-fi client will not appear on the list of connected clients as if it didn't exist. On the client side, however, the client will acquire a 192.168.2.x address and a 192.168.2.1 gateway which are of course wrong and will not work correctly.

After disconnecting and reconnecting repeatedly the correct address range will eventually be served.

This happens on different iPhones as well as laptops and also other connected devices. 

 

Any help is really appreciated

 

Thanks

 

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#1
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1 Accepted Solution
Re:Re:Re:DHCP not working correctly-Solution
2019-04-17 23:50:45 - last edited 2019-04-18 01:24:47

The mystery is solved: I had a wired ethernet device with an active DHCP server on it. It was such device that was responding to some of my DHCP queries... Thanks for the help anyways!

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#4
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4 Replies
Re:DHCP not working correctly
2019-04-17 07:22:39

Hi,

 

So, the LAN IP of your Archer A6 is actually 192.168.0.1 not 192.168.2.1.

 

In this case, could you please tell me if you have any other wireless network like another router, modem router, range extender or access point?

 

Could you please use a laptop to do a ipconfig/all and then put in arp -a on cmd windows when the IP becomes 192.168.2.x? And please check if the MAC address on your router Archer A6 is same or not as the MAC you got on arp -a? (Do not tell the MAC here since it is private information).

 

If the MAC is not same as router's when IP is 192.168.2.x, that means IP is not from A6 but from something else, you may need to locate what the device is.

 

Good day!

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#2
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Re:Re:DHCP not working correctly
2019-04-17 11:33:17

Hello Kevin,

 

As in any densely populated area I have plenty of Wi-Fi devices in range. However I own no range extenders, nor other routers. 

As you can see below, MAC addresses in the two situations do differ. When the expected range is assigned, the MAC of the router's address matches the MAC printed on the chassis of my Archer A6. When the mystery range is assigned, instead, the MAC differs

 

Note: this equally happens on both 2GHz and 5GHz ports. When the Archer VPN feature is enabled the problem seems to be happening more often, but it also happens when the VPN is disabled.

 

My question at this point is: is it possible that my router is - for whatever reason - responding with a different MAC address or does that necessairily mean I am connecting to a different unknown device?

 

Thanks again

 

Alains-MacBook:~ alain$ ifconfig | grep ^en0 -A 6
en0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
    ether 78:**:**:**:**:8a
    inet6 fe80::***:***:***:63f5%en0 prefixlen 64 secured scopeid 0x5
    inet 192.168.0.178 netmask 0xffffff00 broadcast 192.168.0.255
    nd6 options=201<PERFORMNUD,DAD>
    media: autoselect
    status: active
Alains-MacBook:~ alain$ arp -a
? (192.168.0.1) at 68:**:**:**:**:c9 on en0 ifscope [ethernet]
? (192.168.0.124) at 50:**:**:**:**:78 on en0 ifscope [ethernet]
? (192.168.0.255) at ff:ff:ff:ff:ff:ff on en0 ifscope [ethernet]
? (224.0.0.251) at 1:**:**:**:**:fb on en0 ifscope permanent [ethernet]
? (239.255.255.250) at 1:**:**:**:**:fa on en0 ifscope permanent [ethernet]
broadcasthost (255.255.255.255) at ff:ff:ff:ff:ff:ff on en0 ifscope [ethernet]
Alains-MacBook:~ alain$
Alains-MacBook:~ alain$
Alains-MacBook:~ alain$
Alains-MacBook:~ alain$
Alains-MacBook:~ alain$ ifconfig | grep ^en0 -A 6
en0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
    ether 78:**:**:**:**:8a
    inet6 fe80::**:**:**:63f5%en0 prefixlen 64 secured scopeid 0x5
    inet 192.168.2.104 netmask 0xffffff00 broadcast 192.168.2.255
    nd6 options=201<PERFORMNUD,DAD>
    media: autoselect
    status: active
Alains-MacBook:~ alain$ arp -a
? (192.168.2.1) at 0:**:**:**:**:24 on en0 ifscope [ethernet]
? (192.168.2.255) at ff:ff:ff:ff:ff:ff on en0 ifscope [ethernet]
? (224.0.0.251) at 1:**:**:**:**:fb on en0 ifscope permanent [ethernet]
? (239.255.255.250) at 1:**:**:**:**:fa on en0 ifscope permanent [ethernet]

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#3
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Re:Re:Re:DHCP not working correctly-Solution
2019-04-17 23:50:45 - last edited 2019-04-18 01:24:47

The mystery is solved: I had a wired ethernet device with an active DHCP server on it. It was such device that was responding to some of my DHCP queries... Thanks for the help anyways!

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#4
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Re:Re:Re:Re:DHCP not working correctly
2019-04-18 01:23:37

Hi,

 

Great to know that it was solved finally. and thanks for your valued feedback. 

 

To ensure that the devices get the correct/expected IP address, multiple DHCP servers must be avoided, otherwise, they may obtain IP address in a different subnet. 

 

And do not hesitate to contact us if need more help.

 

Good day. 

 

Alain2 wrote

The mystery is solved: I had a wired ethernet device with an active DHCP server on it. It was such device that was responding to some of my DHCP queries... Thanks for the help anyways!

 

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#5
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