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Archer AX21 in Access Point mode sends DHCPREQUEST every 33 seconds

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Archer AX21 in Access Point mode sends DHCPREQUEST every 33 seconds

This thread has been locked for further replies. You can start a new thread to share your ideas or ask questions.
Archer AX21 in Access Point mode sends DHCPREQUEST every 33 seconds
Archer AX21 in Access Point mode sends DHCPREQUEST every 33 seconds
2021-01-25 02:33:06
Model: Archer A20  
Hardware Version: V1
Firmware Version: 1.2.1 Build 20201202 rel.76564(5553)

I recently set up an AX1800 in 'Access Point mode' - connected to my home LAN on which I have a linux box offering dhcp.

My LAN port is requesting ( and getting ) a dhcp. I see that it's received the IP I configured for it  ( via mac address in my dhcpd.conf).

 

However, it appears to be re-requesting it every 30-ish seconds :

 

Jan 24 20:50:13 dobby dhcpd[5571]: DHCPREQUEST for 192.168.11.3 from 84:d8:1b:79:45:d4 via enp1s0
Jan 24 20:50:13 dobby dhcpd[5571]: DHCPACK on 192.168.11.3 to 84:d8:1b:79:45:d4 via enp1s0
Jan 24 20:50:45 dobby dhcpd[5571]: DHCPREQUEST for 192.168.11.3 from 84:d8:1b:79:45:d4 via enp1s0
Jan 24 20:50:45 dobby dhcpd[5571]: DHCPACK on 192.168.11.3 to 84:d8:1b:79:45:d4 via enp1s0
Jan 24 20:51:18 dobby dhcpd[5571]: DHCPREQUEST for 192.168.11.3 from 84:d8:1b:79:45:d4 via enp1s0
Jan 24 20:51:18 dobby dhcpd[5571]: DHCPACK on 192.168.11.3 to 84:d8:1b:79:45:d4 via enp1s0
Jan 24 20:51:18 dobby dhcpd[5571]: DHCPINFORM from 192.168.11.83 via enp1s0
Jan 24 20:51:18 dobby dhcpd[5571]: DHCPACK to 192.168.11.83 (ec:f4:bb:10:4d:8e) via enp1s0
Jan 24 20:51:50 dobby dhcpd[5571]: DHCPREQUEST for 192.168.11.3 from 84:d8:1b:79:45:d4 via enp1s0
Jan 24 20:51:50 dobby dhcpd[5571]: DHCPACK on 192.168.11.3 to 84:d8:1b:79:45:d4 via enp1s0
Jan 24 20:52:22 dobby dhcpd[5571]: DHCPREQUEST for 192.168.11.3 from 84:d8:1b:79:45:d4 via enp1s0
Jan 24 20:52:22 dobby dhcpd[5571]: DHCPACK on 192.168.11.3 to 84:d8:1b:79:45:d4 via enp1s0
Jan 24 20:52:54 dobby dhcpd[5571]: DHCPREQUEST for 192.168.11.3 from 84:d8:1b:79:45:d4 via enp1s0
Jan 24 20:52:54 dobby dhcpd[5571]: DHCPACK on 192.168.11.3 to 84:d8:1b:79:45:d4 via enp1s0
 

My  dhcpd config looks like this :

 

subnet 192.168.11.0 netmask 255.255.255.0 {
 

      options... { blah blah}

 

        default-lease-time 21600;
        max-lease-time 43200;
 

        pool {
                allow unknown-clients;
                range 192.168.11.80 192.168.11.250;
        }
 

host wireless {
        hardware ethernet 84:d8:1b:79:45:d4;
        fixed-address 192.168.11.3;
        }
 

host blah {

   hardware blah

  fixed-address more blah

 }

 

}

 

 

It has a static IP assigned outside of the dynamic pool - but keeps asking...

I've got a bunch of other devices which I set up similarly - regular PC's and servers and the like, none of which exhibit this beahviour.

 

 

 

 

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#1
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6 Reply
Re:Archer AX21 in Access Point mode sends DHCPREQUEST every 33 seconds
2021-01-25 08:17:38

@SLawrence 

 

Hello, is the model Archer AX1800? Can you please check if the Smart DHCP on it is still on, it will continuously check if the DHCP server on the network is correctly on when it is enabled, you can disable the DHCP server on the AX1800, and choose static IP for the LAN, there won't be an issue then:

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#2
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Re:Archer AX21 in Access Point mode sends DHCPREQUEST every 33 seconds
2021-01-25 09:20:15 - last edited 2021-01-25 09:21:51

@Kevin_Z 

 

It's an AX1800, yes. I was unable to select the model / firmware sufficiently in the dropdown when you make a post, but it refers to itself like this :

 

 

I'm not entirely sure what 'Smart DHCP' is... But it's off.

 

 

Setting a static IP on my (wireless) router defeats the point of me assigning one on my DHCP server. I shouldn't have to set a device static'ly when I can configure it on my server and have it auto-update, instead of having to visit each device in turn and/or have to troubleshoot it if or when the lan subnet changes. The whole *point* is that I can update my lan and have devices continue to function when that happens. 

 

In addition, I'm not sure that the 'dhcp server' on the AX wireless would have anything to do with the LAN side IP requesting its own from my gateway box. The two should be independent?

 

This really *should* be the most simple setup possible. Access point.. DHCP address for the LAN side, pass-through for the WAN side. -  And that *does* happen. Devices connecting wirelessly are *correctly* getting passed through to my dhcp server, getting an address and sticking with it - no re-requests. It's ONLY the LAN side port(s) which keeps re-requesting.

 

For good measure. I restarted my dhcp server and rebooted the AX1800 - I get this :

 

Jan 25 04:02:31 dobby dhcpd[14078]: DHCPRELEASE of 192.168.11.3 from 84:d8:1b:79:45:d4 via enp1s0 (not found)

 

release before reboot...

 

Jan 25 04:03:32 dobby dhcpd[14078]: DHCPDISCOVER from 84:d8:1b:79:45:d4 via enp1s0
Jan 25 04:03:32 dobby dhcpd[14078]: DHCPOFFER on 192.168.11.3 to 84:d8:1b:79:45:d4 via enp1s0
Jan 25 04:03:32 dobby dhcpd[14078]: DHCPREQUEST for 192.168.11.3 (192.168.11.1) from 84:d8:1b:79:45:d4 via enp1s0
Jan 25 04:03:32 dobby dhcpd[14078]: DHCPACK on 192.168.11.3 to 84:d8:1b:79:45:d4 via enp1s0

 

when it boots back up - a discover, offer from my server, request and ACK - all normal.

 

 

Jan 25 04:03:43 dobby dhcpd[14078]: DHCPREQUEST for 192.168.11.83 from ec:f4:bb:10:4d:8e (steve-laptop) via enp1s0
Jan 25 04:03:43 dobby dhcpd[14078]: DHCPACK on 192.168.11.83 to ec:f4:bb:10:4d:8e (steve-laptop) via enp1s0
Jan 25 04:03:43 dobby dhcpd[14078]: DHCPINFORM from 192.168.11.83 via enp1s0
Jan 25 04:03:43 dobby dhcpd[14078]: DHCPACK to 192.168.11.83 (ec:f4:bb:10:4d:8e) via enp1s0

 

A laptop connected to one of the network ports in the wireless router makes a request - gets back an offer, and ACK's it.

 

Jan 25 04:04:04 dobby dhcpd[14078]: DHCPREQUEST for 192.168.11.3 from 84:d8:1b:79:45:d4 via enp1s0
Jan 25 04:04:04 dobby dhcpd[14078]: DHCPACK on 192.168.11.3 to 84:d8:1b:79:45:d4 via enp1s0
Jan 25 04:04:36 dobby dhcpd[14078]: DHCPREQUEST for 192.168.11.3 from 84:d8:1b:79:45:d4 via enp1s0
Jan 25 04:04:36 dobby dhcpd[14078]: DHCPACK on 192.168.11.3 to 84:d8:1b:79:45:d4 via enp1s0

Jan 25 04:05:08 dobby dhcpd[14078]: DHCPREQUEST for 192.168.11.3 from 84:d8:1b:79:45:d4 via enp1s0
Jan 25 04:05:08 dobby dhcpd[14078]: DHCPACK on 192.168.11.3 to 84:d8:1b:79:45:d4 via enp1s0
Jan 25 04:05:41 dobby dhcpd[14078]: DHCPREQUEST for 192.168.11.3 from 84:d8:1b:79:45:d4 via enp1s0
Jan 25 04:05:41 dobby dhcpd[14078]: DHCPACK on 192.168.11.3 to 84:d8:1b:79:45:d4 via enp1s0
Jan 25 04:06:13 dobby dhcpd[14078]: DHCPREQUEST for 192.168.11.3 from 84:d8:1b:79:45:d4 via enp1s0
Jan 25 04:06:13 dobby dhcpd[14078]: DHCPACK on 192.168.11.3 to 84:d8:1b:79:45:d4 via enp1s0
Jan 25 04:06:45 dobby dhcpd[14078]: DHCPREQUEST for 192.168.11.3 from 84:d8:1b:79:45:d4 via enp1s0
Jan 25 04:06:45 dobby dhcpd[14078]: DHCPACK on 192.168.11.3 to 84:d8:1b:79:45:d4 via enp1s0
Jan 25 04:07:17 dobby dhcpd[14078]: DHCPREQUEST for 192.168.11.3 from 84:d8:1b:79:45:d4 via enp1s0
Jan 25 04:07:17 dobby dhcpd[14078]: DHCPACK on 192.168.11.3 to 84:d8:1b:79:45:d4 via enp1s0

 

And everything thereafter is the AX1800's LAN port re-requesting its IP every 32 seconds. It's like it's not honouring the lease time... 

 

 

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#3
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Re:Archer AX21 in Access Point mode sends DHCPREQUEST every 33 seconds
2021-01-25 10:52:56

@SLawrence 

 

Hi, thanks for getting back with detailed info. To locate this issue and try to fix it, we would like to follow up on your case via email. Please check your inbox and provide the information that we need.

If you found a post or response helpful, please click Helpful (arrow pointing upward icon). If you are the author of a topic, remember to mark a helpful reply as the "Recommended Solution" (star icon) so that others can benefit from it.
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#4
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Re:Archer AX21 in Access Point mode sends DHCPREQUEST every 33 seconds
2021-03-30 16:58:46

@Kevin_Z 

 

Following up on this. 

After doing the requested troubleshooting, I got this : 

 

We feedbacked this issue to the testing department last week. After testing, AX21 does have this unreasonable mechanism. 
 
We have registered this issue in the feedback system that we use to feedback issues to the R&D department. 
If the R&D department thinks this is a software problem, they will fix it in the firmware later. 
 
If the R&D department considers this to be a reasonable mechanism, I will email their explanation to you. 
 

Which was a couple of months back.

Any word on a fix?

 

Steve.

 
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#5
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Re:Archer AX21 in Access Point mode sends DHCPREQUEST every 33 seconds
2021-03-31 02:25:38

@SLawrence 

 

Hi, please confirm the issue status with the engineer directly, they will help with the follow-up.

If you found a post or response helpful, please click Helpful (arrow pointing upward icon). If you are the author of a topic, remember to mark a helpful reply as the "Recommended Solution" (star icon) so that others can benefit from it.
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#6
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Re:Archer AX21 in Access Point mode sends DHCPREQUEST every 33 seconds
2021-08-07 20:25:05 - last edited 2021-08-07 20:26:00

@SLawrence 

 

In case anyone else ever searches for a similar problem, my experience went as follows :

 

Someone ( not a developer) asked me to provide detailed tcpdump logs - which I did, and they acknowledged that there was indeed a problem.

Some time after, I chased up, at which point the admission was retracted and changed to 'this is how it should behave'.

 

I pointed out that that statement is contrary to the workings of DHCP ( should obey the lease time) at which point.. the whitewashing began.

 
     I'm sorry, but the R&D department may not modify this design.
 
     Yes, at first I thought this was an unreasonable mechanism, so after that I went and contacted our R&D department and they told me they designed it that way to make sure          AX21 would still work if the DHCP Server on the main router crashed.
 
which is utter garbage. After all - if your dhcpd server crashed then your unit is not going to get an IP and render itself inoperable AFTER 30 SECONDS. At least, given a lease time of say, 1 day it would continue to operate. 
 
A couple of further mails resulted in : 
 
     I admit I am almost convinced by you, I will tell your idea to the R&D department and hopefully they will make changes to the existing firmware.
 
 

At which point I gave up and returned the units as 'unfit for purpose'.

 

 
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#7
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Views: 500

Replies: 6

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