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Re: No DHCP for Wireless Clients

[ Edited ]

@ecenet can you do an 802.11 capture of the exchange?  Something that I migh not have been clear about in previous posts is that an 802.11 and 802.3 capture on the MacBook are not necessarily the same.  It's possible for a client to receieve someothing on it's wireless interface and drop it before tcpdump has a chance to capture the packet. 

 

The same is true on the AP.  tcpdump of athX does not guarantee that the packet is sent over the air.

 

So, again, for those that are seeing the problem persist, an 802.11 capture is going to be the most useful.

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Re: No DHCP for Wireless Clients

@jfruehe can you explain what multicast VLAN means?  Or, can you explain more about that configuration?

 

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Re: No DHCP for Wireless Clients


@UBNT-BenBuckley wrote:

@jfruehe can you explain what multicast VLAN means?  Or, can you explain more about that configuration?

 


I had problems with Apple devices getting DHCP IPs, static would work fine, but could not get a lease. I tried everything. 

 

In my configuration I had a VLAN that was only used for 2 devices, an HDMI transmitter (over Ethernet) that uses multicast and an HDMI receiver. The 2 devices were on a VLAN and *theoretically* the traffic was separate from the rest of the traffic. All of my other devices could get IPs, both in 2.4 and 5GHz on any of the APs.

 

If you recall, the devices would power on, connect, get an IP for ~8-10 seconds, then lose the IP. After a minute or two, in most cases, they would reestablish a connection and hold the IP. Very frustrating.

 

Finally, I enabled IGMP Snooping on the VLAN and that solved all of my problems. Since that time (probably a week or more) the system is running great. No DHCP issues at all. 

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Re: No DHCP for Wireless Clients

@jfruehe If I understand right, you have a VLAN with only two devices on it (HDMI over ENET).  On your other VLAN (the one using RADIUS, that you'd previously had issues with) did you have settings configured to disable bcast/mcast data or something?

Trying to understand why you called it the multicast VLAN.  

 

Also, if enabling IGMP snoopong on that VLAN fixed the DHCP issues on your other VLAN, I'd like to understand why.  Are you willing to give me remote access to your controller (or send me a backup of it) so I can see how the VLAN's and bcast/mcast settings are configured?

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Re: No DHCP for Wireless Clients


@UBNT-BenBuckley wrote:

@ecenet can you do an 802.11 capture of the exchange? 

 

[... ] 

 

The same is true on the AP.  tcpdump of athX does not guarantee that the packet is sent over the air.

 

So, again, for those that are seeing the problem persist, an 802.11 capture is going to be the most useful.


@UBNT-BenBuckley, not sure exactly what you need.

 

How do I capture a raw 802.11 on.. 

 

A) a Windows device?

B) on a Unifi AP? 

 

I thought capturing packets on a Window's network interface in promiscuous mode would capture anything and everything? 

Same for the Linux device and capturing with tcpdump on athX. 

 

 

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Re: No DHCP for Wireless Clients


@UBNT-BenBuckley wrote:

@jfruehe If I understand right, you have a VLAN with only two devices on it (HDMI over ENET).  On your other VLAN (the one using RADIUS, that you'd previously had issues with) did you have settings configured to disable bcast/mcast data or something?

Trying to understand why you called it the multicast VLAN.  

 

Also, if enabling IGMP snoopong on that VLAN fixed the DHCP issues on your other VLAN, I'd like to understand why.  Are you willing to give me remote access to your controller (or send me a backup of it) so I can see how the VLAN's and bcast/mcast settings are configured?


I am happy to give you a backup of it. I'm running on MacOS, so let me know what the files are that you want and I will zip them up and put them on my FTP for you.

 

When I called it a "multicast VLAN" what I really meant was "a VLAN to segment my multicast devices." I actually have two of them, VLAN 200 needs to traverse multiple switches, turning on IGMP Snooping fixed things. VLAN 300 is all containted on one switch and the uplink on that switch is not tagged so I did not need to enable IGMP Snooping.

 

Here is VLAN 200:

Screen Shot 2018-11-12 at 3.45.10 PM.png

 

Here is VLAN 300:

 

Screen Shot 2018-11-12 at 3.46.34 PM.png

 

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Re: No DHCP for Wireless Clients

@jfruehe just go to Settings -> Site -> Export Site and give me a link to that file. I will import it and be able to see you're settings.

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Re: No DHCP for Wireless Clients

Sent you a PM with the link, let me know if that works for you.

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Re: No DHCP for Wireless Clients


@ecenet wrote:

@UBNT-BenBuckley wrote:

@ecenet can you do an 802.11 capture of the exchange? 

 

[... ] 

 

The same is true on the AP.  tcpdump of athX does not guarantee that the packet is sent over the air.

 

So, again, for those that are seeing the problem persist, an 802.11 capture is going to be the most useful.


@UBNT-BenBuckley, not sure exactly what you need.

 

How do I capture a raw 802.11 on.. 

 

A) a Windows device?

B) on a Unifi AP? 

 

I thought capturing packets on a Window's network interface in promiscuous mode would capture anything and everything? 

Same for the Linux device and capturing with tcpdump on athX. 

 

 


@UBNT-BenBuckley, could you kindly verify what information you need from my end? I'd like to see this issue resolved as soon as possible. We have two clients with 30+ APs and they're quite unhappy with the current situation Man Sad

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Re: No DHCP for Wireless Clients

@ecenet a quick google search got me this: https://wiki.wireshark.org/CaptureSetup/WLAN#Windows

 

You cant really do an 802.11 capture from a UniFi AP.  

 

tpcdump will only give you 802.11 packets if you've created a wireless interface in monitor mode, which you probably didnt.  

 

In terms of troubleshooting, I recommend double checking your configuration.  @jfruehe's issue ended up being config related.

 

If you have any reason to suggest that it's a bug (for example, it works on FW version X, but when I upgrade to Y it breaks.  But if I go back to X it works again, and then back to Y fails again) then I can continue to dig in further.  

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Re: No DHCP for Wireless Clients

@jfruehe I imported your site to take a look, and some of it doens't match up to the dicusssion we've had in this thread.  For example, the site import didn't even have an 802.x (RADIUS) wireless network. 

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Re: No DHCP for Wireless Clients


@UBNT-BenBuckley wrote:

@ecenet a quick google search got me this: https://wiki.wireshark.org/CaptureSetup/WLAN#Windows

 

You cant really do an 802.11 capture from a UniFi AP.  

 

tpcdump will only give you 802.11 packets if you've created a wireless interface in monitor mode, which you probably didnt.  

 

In terms of troubleshooting, I recommend double checking your configuration.  @jfruehe's issue ended up being config related.

 

If you have any reason to suggest that it's a bug (for example, it works on FW version X, but when I upgrade to Y it breaks.  But if I go back to X it works again, and then back to Y fails again) then I can continue to dig in further.  


@UBNT-BenBuckley, I thought you have capture 802.11 before before because you have asked for a 802.11 capture - that's why I have asked you. I will try to capture this from a Mac laptop.

 

The fact that restarting the APs fixes the issue for a while (on APs with little traffic) indicates that it is likely a bug and not a configuration issue. However, I have checked the config already a couple of times and can't find anything odd - would it be possible for you to have a look? It's really very basic - not much which can/should go wrong.

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Re: No DHCP for Wireless Clients

@ecenet rebooting AP's will kick all of the clients off of an AP and cause them to connect to another AP, which can sometimes look like it's fixing the issue when it's not.

 

But sure, invite me to your controller and I will take a quick look.

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Re: No DHCP for Wireless Clients


@UBNT-BenBuckley wrote:

@ecenet rebooting AP's will kick all of the clients off of an AP and cause them to connect to another AP, which can sometimes look like it's fixing the issue when it's not.

 

But sure, invite me to your controller and I will take a quick look.


@UBNT-BenBuckley, I am restarting the AP which I was connected before and I made sure I am connecting to the same one (sitting right by the AP, the next one is considerably further away).

How can I directly invite you the the controller?

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Re: No DHCP for Wireless Clients


@UBNT-BenBuckley wrote:

@jfruehe I imported your site to take a look, and some of it doens't match up to the dicusssion we've had in this thread.  For example, the site import didn't even have an 802.x (RADIUS) wireless network. 


I am using WPA Personal, not Enterprise. Is RADIUS required for a home network?

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Re: No DHCP for Wireless Clients

I am going to recall that changing DTIM fixed the issue for me. I still have this issue, where RADIUS clients can connect, but do not receive DHCP. Rebooting the WAP(s) will fix the issue immediately but only for an indeterminant amount of time. This just happened again this morning, no one could connect. Reboot the WAP's and then everything is perfect. Since the last time this happened, things had been running for several days (>5d).

 

Just to reiterate, AP-AC-LR's, 3.9.54.9373, 5.6.40 controller. Only saw this issue after upgrading to 3.9.54.

 

Lastly, how to check what the current DTIM value is? i see "Use Default Values" is checked (although I have tried unchecking and forcing to 3 and other values), but what value will it use when Use Default Values is checked and how to confirm? Regardless, i dont think DTIM value is causing this issue, but some other bug in the firmware.

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Re: No DHCP for Wireless Clients

Only 3.9.19.8123 works for me on AP-AC-LR and AP-AC-Pro. Tried every other newer FW including 3.9.54.9373 but with no luck. 

Also this DHCP issue may be somehow connected with NPS server error 6273 (reason code 65) but I'm not shure.

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Re: No DHCP for Wireless Clients

I don't have that error on my NPS. In fact, NPS is working ok, because when I have the issue and the client connects, I can see it successfully passes the policy through my logging and in fact, does connect to the wireless network, just never gets the DHCP offer. Also if this is the case, restarting the WAP wouldn't fix an NPS issue.
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Re: No DHCP for Wireless Clients

Thanks for your post, @Resverlogix. I am in contact with the Ubiquiti team, and it is good to know, that there are other users who experience similar issues as well.

 

Current status:

It looks like it is *not* limited to RADIUS authenticated clients. I was able to reproduce this behaviour with a regular WPA-PSK wifi. I was able to capture logs which shows the same behaviour as the other users have posted:

 

I have captured packets:

 

- on the client

- on the DHCP server

- on the AP (port mirroring and tcpdumping on athX)

 

I can see the DHCP DISCOVER properly received by the server.

I can see the DHCP OFFER sent from the DHCP server.

I can see the DHCP OFFER arriving on the port where the AP sits

I can see the DHCP OFFER showing up on the tcpdump running on the AP

But the packet never arrives on the client. Reproducable!

 

As said.. restarting the AP fixes the issue for a while.

 

At first the UBNT team assumed it has something to do with my configuration and my setup and my "misconfiguration" - however, we have double and triple checked the setup and can't find any issues. Access has been granted to our config and their team could not find anything odd so far.

 

I was able to capture 802.11 traffic using a MacBook, but I am having issues decoding the captures - is anyone able to assist me here?

 

If we can prove that the DHCP OFFER packets are NOT on the 802.11 captures, this proves that the APs are filtering out the packets. As said, all my captures (see above) indicate that this is happening.

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Re: No DHCP for Wireless Clients

I am having the same issue but only it seems with Radius clients. Some clients are fine others are not.

 

WireShark looks clean on the DHCP server, but offer never shows up on the client. So same as everybody else it seems. I am on Controller 5.9.29 fimrware 3.9.54, I have lost track if there seems to be a firmware that does solve the problem!

 

 

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