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Registered: ‎07-14-2016

Re: No DHCP for Wireless Clients

@g357130- I forced provision on the one I was testing, and, now I can't repro the issue... was going to start the firmware downgrade/eval process to find the issue, but, decided to do a force provision first. After that, I haven't been able to repro the problem. Before that, I could easily repro.

 

I know some people have said that it may take some time before it craps out again.. so.. we'll see. And, not really sure if @jfruehe's issue is the same thing - as, when it doesn't work, it never works - attempting renewals of DHCP never does anything.. maybe the Mac is trying to be smart and flip between 2.4 and 5 radios.. if that is the case, then, it could be the same issue. @jfruehe - maybe you should try disabling your 5ghz radio on the Mac or the UAP and see if the problem goes away.

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Re: No DHCP for Wireless Clients


@slash1 wrote:

@g357130- I forced provision on the one I was testing, and, now I can't repro the issue... was going to start the firmware downgrade/eval process to find the issue, but, decided to do a force provision first. After that, I haven't been able to repro the problem. Before that, I could easily repro.

 

I know some people have said that it may take some time before it craps out again.. so.. we'll see. And, not really sure if @jfruehe's issue is the same thing - as, when it doesn't work, it never works - attempting renewals of DHCP never does anything.. maybe the Mac is trying to be smart and flip between 2.4 and 5 radios.. if that is the case, then, it could be the same issue. @jfruehe - maybe you should try disabling your 5ghz radio on the Mac or the UAP and see if the problem goes away.


I will try that later today. Based on the connection speed I know I am connected at 5ghz

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Re: No DHCP for Wireless Clients

[ Edited ]

@jfruehe You can also see which band the Mac is connected to by Optoin + click the WiFi icon. It will show channel, BSSID, bandwidth, etc.  It's really quite nice.

 

The iperf result doens't surprise me... I see results like that when the client roams during the test, or there is some outside interference (another client doing something on the network).

 

As for losing the DHCP lease... the device will only do DHCP upon initial connection.  So if it get's the lease, then drops it, that indicates that the deviec is roaming AP's, or is roaming from 2G to 5G.  Can you alter your test set-up to prohibit roaming activity by the laptop?  Do this by either chaning the SSID of 2G and 5G, or by disabling one or the other during the test?

 

I wonder if there is some sort of race condition when your laptop can't decide which band to connect to.  The frequent/unexpected roam might be causing the AP to route traffic incorrrectly, or something like that.

 

Can you refresh my memory if you have Band Steering, Fast Roaming, or any other advanced features enabled?

 

One last thing, have you rebooted your laptop recently?  I've been recently doing some testing where I force the AP to be picky about which radio it allows my iPhone and MBP to connect to, and it can get my Apple devices into a funny state where they have to be rebooted to get them working correctly again.  So it's possible that there is sufficient roaming/retry activity on the laptop that it's blacklisting the network for a short time.

 

If you'd like to try our latest features, consider signing up for beta: https://help.ubnt.com/hc/en-us/articles/204908664-How-To-Sign-Up-for-Beta-Access

If you're trying to debug a network issue, take a look at this help article: https://help.ubnt.com/hc/en-us/articles/221029967-UniFi-Debugging-Intermittent-Connectivity-Issues-on-your-UAP
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Re: No DHCP for Wireless Clients


@UBNT-BenBuckley wrote:

@jfruehe You can also see which band the Mac is connected to by Optoin + click the WiFi icon. It will show channel, BSSID, bandwidth, etc.  It's really quite nice.

 

The iperf result doens't surprise me... I see results like that when the client roams during the test, or there is some outside interference (another client doing something on the network).

 

As for losing the DHCP lease... the device will only do DHCP upon initial connection.  So if it get's the lease, then drops it, that indicates that the deviec is roaming AP's, or is roaming from 2G to 5G.  Can you alter your test set-up to prohibit roaming activity by the laptop?  Do this by either chaning the SSID of 2G and 5G, or by disabling one or the other during the test?

 

I wonder if there is some sort of race condition when your laptop can't decide which band to connect to.  The frequent/unexpected roam might be causing the AP to route traffic incorrrectly, or something like that.

 

Can you refresh my memory if you have Band Steering, Fast Roaming, or any other advanced features enabled?

 

One last thing, have you rebooted your laptop recently?  I've been recently doing some testing where I force the AP to be picky about which radio it allows my iPhone and MBP to connect to, and it can get my Apple devices into a funny state where they have to be rebooted to get them working correctly again.  So it's possible that there is sufficient roaming/retry activity on the laptop that it's blacklisting the network for a short time.

 


I use a WiFi utility and it always shows me connected to the 5GHz band, whether I have an internet connection or am searching for a connection.

 

I will try to disable 5GHz on that AP and see if the same DHCP problem exists.

 

I know there is no interference because this is in my home and it acts exactly the same way, connects for a second, drops for a minute then connects for as long as I am using it. The pattern is so precise that it cannot be environmental.

 

As to other traffic, this morning's testing happend at 4:30AM when I was the only person awake.

 

Will check on the other advanced features later today.

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Re: No DHCP for Wireless Clients

Same issue for us, Mac (Mojave) connects to the Wireless AP but doesnt get an IP/DHCP lease, but only when connecting to our corporate RADIUS backed SSID. WPA2 (we run for Guest access) never has a problem connecting. Again, these are UAC-AC-LR WAP's, running 3.9.54.9373 firmware (5.6.40 controller). Problem for us seemed to kick in after firmware update of the WAP's. Strange though that on my other site where it is all HP Windows 10 laptops, I have never seen this issue yet (same AP's and same firmware), so it could be some issue with Mac as the user recently updated to Mojave. I tried disabling 5Ghz on the RADIUS SSID on the AP and so far they seem to connect right away now and get proper DHCP lease. I agree with others, that this is something with the AP.
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Re: No DHCP for Wireless Clients


@UBNT-BenBuckley wrote:

@jfruehe You can also see which band the Mac is connected to by Optoin + click the WiFi icon. It will show channel, BSSID, bandwidth, etc.  It's really quite nice.

 

The iperf result doens't surprise me... I see results like that when the client roams during the test, or there is some outside interference (another client doing something on the network).

 

As for losing the DHCP lease... the device will only do DHCP upon initial connection.  So if it get's the lease, then drops it, that indicates that the deviec is roaming AP's, or is roaming from 2G to 5G.  Can you alter your test set-up to prohibit roaming activity by the laptop?  Do this by either chaning the SSID of 2G and 5G, or by disabling one or the other during the test?

 

I wonder if there is some sort of race condition when your laptop can't decide which band to connect to.  The frequent/unexpected roam might be causing the AP to route traffic incorrrectly, or something like that.

 

Can you refresh my memory if you have Band Steering, Fast Roaming, or any other advanced features enabled?

 

One last thing, have you rebooted your laptop recently?  I've been recently doing some testing where I force the AP to be picky about which radio it allows my iPhone and MBP to connect to, and it can get my Apple devices into a funny state where they have to be rebooted to get them working correctly again.  So it's possible that there is sufficient roaming/retry activity on the laptop that it's blacklisting the network for a short time.

 


OK, I played with turning each band off. Both acted exactly the same. Whether it was 2.4GHz or 5GHz, I would turn WiFi on, it would connect for a few seconds, drop and then connect again after about 1-1.5 minutes. Then it would be solid.

 

Here is a snapshot of my network:

 

Screen Shot 2018-11-01 at 7.18.53 PM.jpg

 

I am connected to the bottom one (in red). As you can see it is far enough away that it should not be roaming to the downstairs. 

 

Sure, but maybe one of your neighbors is interfering? Nope:

 

Screen Shot 2018-11-01 at 7.25.59 PM.jpg

 

No fast roaming, no minimum RSSI, don't see a band steering option.

 

 

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Re: No DHCP for Wireless Clients


@Resverlogix wrote:
Same issue for us, Mac (Mojave) connects to the Wireless AP but doesnt get an IP/DHCP lease, but only when connecting to our corporate RADIUS backed SSID. WPA2 (we run for Guest access) never has a problem connecting. Again, these are UAC-AC-LR WAP's, running 3.9.54.9373 firmware (5.6.40 controller). Problem for us seemed to kick in after firmware update of the WAP's. Strange though that on my other site where it is all HP Windows 10 laptops, I have never seen this issue yet (same AP's and same firmware), so it could be some issue with Mac as the user recently updated to Mojave. I tried disabling 5Ghz on the RADIUS SSID on the AP and so far they seem to connect right away now and get proper DHCP lease. I agree with others, that this is something with the AP.

 

What I am seeing is an immediate connection that lasts less than 10 seconds. Then a drop of DHCP where I am still connected for about 1-1.5 minutes then a reconnection.

 

Have you tried turning WiFi off and on, then letting the MacBook sit for ~1-2 minutes? If you do that, do you get a WiFi signal again?

 

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Re: No DHCP for Wireless Clients

I've forced a re-provision on the UAP AC PROs and set the DTIM value to 3 (from 1) on the 5GHz band and I'm not seeing any issues this morning and am unable to replicate the issue so far.

Those that are hitting the issue, can you check your DTIM value of your 5GHz band on the SSID causing the issue and update the thread?
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Re: No DHCP for Wireless Clients

With DTIM at 1, 3 and even 5 I get the same results.

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Re: No DHCP for Wireless Clients

my DTIM at both sites is set to the default of 1.

 

Funny thing is, our WPA2 SSID works perfectly for the user that is having issues., its only the RADIUS SSID. No problems connecting to the wireless network, just no IP. RADIUS accounting/logging confirms successful authentication too. Since its just the one user and they are at a different site, its hard for me to do any indepth troubleshooting, but I will get them to use it more and report in.

 

It seems like the switching off 5Ghz on the AP the user is connected to helped

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Re: No DHCP for Wireless Clients

[ Edited ]

try a force provision.. that has resolved it for me (so far)......

 

oops.. I lied. Just tried it again.. no love.. so, it would seem that timing has something to do with it as well.. maybe..

New Member
Posts: 11
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Re: No DHCP for Wireless Clients

Downgraded to 3.9.27.8537. Works initially. Will check again in a few days (although, I'm out of town next week.. so.. we'll see).

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Re: No DHCP for Wireless Clients

[ Edited ]

@Resverlogix- Try changing DTIM to 3 on the SSID using Radius on the 5GHz channel (be aware this will reprovision all APs).

From what I understand, new installations of the controller use DTIM 3 by default, and DTIM 1 is a "legacy" setting from older versions of the Unifi Controller (haven't confirmed this though).

@slash1- How about you, are you using DTIM 1 or 3? If 1, try changing it to 3...

 

2018-11-02 16_27_08-fcrad.francisclark.co.uk.png

Rebooting the AP fixes the issue for a short period of time, so I imagine downgrading is going to be similar (but it doesn't fix it long term).

 

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Re: No DHCP for Wireless Clients

I tried a force provision, no go for me either, the issue persisted.
New Member
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Re: No DHCP for Wireless Clients

@g357130I'm "set to default" - 1 and 1.

 

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Re: No DHCP for Wireless Clients


@g357130 wrote:

Would have thought so (it's not enabled here, so I don't believe this will help).

3.9.40.9098 still working well for you @blazenmp?

 

@UBNT-BenBuckleydo you need anything else?


Yes, it is, with over 40 UAP-AC-PROs using WPA/Enterprise (radius).  I'm not seeing the DHCP issue anymore.

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Re: No DHCP for Wireless Clients

I tried DTIM setting (it was still on 1) to 3 and so far I havnt had any issues with the Mac clients or anyone else.

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Re: No DHCP for Wireless Clients

Good to hear it, I haven't seen any issues this week since making the change last Friday.

I am on an older firmware no 3.9.40, so next step will be getting it back up to the latest firmware to see if the issue is reintroduced, but I'm fairly confident at this stage the DTIM change has resolved it.
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Re: No DHCP for Wireless Clients

Just to close out on the DHCP issues, I *think* I have a solution after trying literally everything.

 

I turned on IGMP Snooping on the multicast VLAN that was on the same switch as the AP. This seems to have resolved the problem. No issues on my MacBook Pro, my wife's MacBook or even the new MacBook Air that we just deployed this evening. Phones required a reboot for some reason, but everything is getting an IP and I have removed the static IPs from my wife's systems.

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Re: No DHCP for Wireless Clients


@g357130 wrote:

@UBNT-BenBuckley- I've performed a packet capture on ath0 (tcpdump -i ath0 -w /tmp/dhcpath0.pcapng) and the client.

 

ath0 sees both the Offer and Discover. The Client does not see the offer.

ath0:

2018-10-31 08_24_18-dhcpath0.pcapng.png

 

Client:

clientdhcp.png

 
This is running firmware 3.9.40.9098, so downgrading didn't help. I am also experiencing the same on 3.9.27.85337 and 3.9.42.9152.
 
To recap, the SSID uses 802.1x/Radius and this issue is only affecting the UAC AC Pros. No VLANs. It only affects a small number of clients per AP, and plenty are successfully getting a DHCP lease.

@g357130 @UBNT-BenBuckley - I am experiencing exactly the same issues here. 
 
No VLANs
Two SSIDs - one with regular PSK, the other with RADIUS authentication. 
Windows DHCP server
 
 
RADIUS authenticated SSID causes issues. I have captured packets and my observations are the same:
 
DHCP Discover - correctly sent from client, received by DHCP server
DHCP Offer - correctly sent from DHCP server, port mirroring on the port where the AP is connected shows that the packet is correctly being sent to the AP, the AP's tcpdump shows that the DHCP Offer is correctly received (it shows up) but it never reaches the client
 
Rebooting the AP fixes the issue for some time.
 
No other device connected to that AP. There is very little traffic during the tests.
 
I have opened a ticket with UBNT before, but have not received any feedback on this issue, ticket ID 1524903.
 
Any ideas?
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