E400 2.4 GHz clients loose Internet access randomly

I just replaced 2 Ubiquiti AC APs in a house with 2 e400's (fw: 3.1.1.1-r1).  House is ~2200 sq ft so there is an AP in an open area on the 2nd floor and an AP in the basement with a bunch of connected home devices.  Both have 2 SSIDs (primary and guest) and both SSIDs are transmitting on 2.4 and 5.  

My problem is with the 2.4 radio. The moment we swapped out the UBNT APs with these, all the 2.4 devices in the house stop working at random intervals. They remain connected to the AP (according to the AP) but they stop passing all traffic.  It's like they vanish. We can't connect to them and they can't connect out.  Reboot the device, it re-conects to 2.4 and works for a while and then repeats this issue. I can reboot the AP and same thing.

We have tried auto channels (20 Mhz) and manually set the channels. I have tried a number of different power settings. We turned the power way down on the basement AP since it is within feet of the devices that are connecting to it. Many of those basement devices roam to the 2nd floor AP and this is regardless of what channels we are using. We are not using overlapping channels. WiFi scan does show other devices (neighbors) on the same channels but not tremendous noise levels. SNR levels are between 30 and 60 on the 2.6 devices so should be plenty of signal above noise.  And this does not seem to be an RF issue, it looks more like the 2.4 WLAN stops talking to the network. 

Since most of the connected home devices are 2.4, this has caused most of them to stop working randomly.

5 Ghz devices have no issues (so far).

Fast roaming is off. Band steering has been set to both off and normal - but these are 2.4 only devices. Airtime fairness is on. Multicast is highest basic. Nothing out of the ordinary.

What am I missing? Anyone else see issues on the 2.4 radio like this?


@Au Wireless wrote:

I just replaced 2 Ubiquiti AC APs in a house with 2 e400's (fw: 3.1.1.1-r1).  House is ~2200 sq ft so there is an AP in an open area on the 2nd floor and an AP in the basement with a bunch of connected home devices.  Both have 2 SSIDs (primary and guest) and both SSIDs are transmitting on 2.4 and 5.  

My problem is with the 2.4 radio. The moment we swapped out the UBNT APs with these, all the 2.4 devices in the house stop working at random intervals. They remain connected to the AP (according to the AP) but they stop passing all traffic.  It's like they vanish. We can't connect to them and they can't connect out.  Reboot the device, it re-conects to 2.4 and works for a while and then repeats this issue. I can reboot the AP and same thing.

We have tried auto channels (20 Mhz) and manually set the channels. I have tried a number of different power settings. We turned the power way down on the basement AP since it is within feet of the devices that are connecting to it. Many of those basement devices roam to the 2nd floor AP and this is regardless of what channels we are using. We are not using overlapping channels. WiFi scan does show other devices (neighbors) on the same channels but not tremendous noise levels. SNR levels are between 30 and 60 on the 2.6 devices so should be plenty of signal above noise.  And this does not seem to be an RF issue, it looks more like the 2.4 WLAN stops talking to the network. 

Since most of the connected home devices are 2.4, this has caused most of them to stop working randomly.

5 Ghz devices have no issues (so far).

Fast roaming is off. Band steering has been set to both off and normal - but these are 2.4 only devices. Airtime fairness is on. Multicast is highest basic. Nothing out of the ordinary.

What am I missing? Anyone else see issues on the 2.4 radio like this?


does the radio have enhanced roaming also enabled? that could cause clients to be disconnected if their signal strength drops low (though you did note the SNR is good).

Is u-apsd enabled or off? (some older clients have trouble with power-save).

COuld you please try turning airtime-fairness off just to see if that is making a difference with some client?

Enhanced roaming is off

Airtime fairness is off for the 2.4 GHz radio (on for the 5 GHz)

UAPSD is off 


@Au Wireless wrote:

Enhanced roaming is off

Airtime fairness is off for the 2.4 GHz radio (on for the 5 GHz)

UAPSD is off 


could you please email a tech-support of the AP (can be downloaded from the 'Operations' section in the device GUI) to support@cambiumnetworks.com. We would need to look at AP logs to see whats going on.

I tried to email that file to you (techsupport.tar.gz) but GMail will not allow me to attach it - illegal file type.  Do you have another method I can get that to you?

I have seen some issues when "proxy ARP" is enabled. I suggest trying with this disabled.

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I have been struggling with this identical issue with at least 3 epmp hotspots for quite some time, at different client locations within our WISP network.  I have tried pretty much every possibie configuration of all parameters, and the problem persists.  Did you finally resolve this issue?  At the suggestion of Cambium tech support, I have configured VLANs and DHCP pools, shortened SSID's, turned off and/ or on every variable and combination thereof for airtime fairness, roaming, power levels, chanel widths, data rates, lease time, proxy ARP, option 82, open security, bandwidth limits, etc., and clients still lose connectivity.  This happens frequently, and is resolved by manually changing any variable, disconnecting all clients, or rebooting.  The only thing I believe Ihave not done yet is replace the devices.

Traffic level definitely is a factor.  During a peak moment yesterday, 2 AP's at the same location rebooted automatically due to Low Memory, according to the system monitor.  We have many other E series devices in our network, but these 3 in particular have the heaviest traffic and the problem is more evident and easier to notice.

When this happens, there is usually (perhaps always) at least 1 device trying to connect but unable to get an IP address.  This happened with the AP functioning simple behind a cnPilot router, and also with the AP functioning as a router, with VLAN and DHCP,  connected directly to our network's RB2011.  We may have 50 with IP addresses from the AP, and 1 without, and nobody can access the Internet.  Error across all devices says connected to AP, but 'no Internet connection'.

Our network is fed by multiple DSL lines running through a load balancing RB2011, in case anybody sees any possible relation there.

i have already sent loads of tech support files, so I am just looking for any related or similar issues, possible solutions or different perspectives at this point.

Hello All
Have you been able to resolve this issue?
We have discovered we have the same issue in a deployment we have where we install 2 É400 per floor in a Hotel…
Kindly advise

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Cambium, have you been able to find any problems and/or solution to this problem?

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I have the same problem, cant reboot the AP's every day, thinking of going back to Unifi

Still no feedback from Cambium on this?! If you want us to swap UniFi with cnPilot, this is a very essential thing that just _got to work_...

I never found a solution to nor source of the problem and grudgingly ended up switching to UniFis at 4 locations (4 HotSpots and 1 E400 exhibiting the same behavior).  Clients who had very much regretted upgrading previously to the ePMP HotSpots are now very happy.  Before switching we did try using other HotSpots, and also tried replacing the HotSpots with E500's.  We also tried removing all the bells and whistles to make these as stupid as the UniFi's hoping for stability, but the same thing continued to happen.  With no solution found nor offerred, I wrote it off to some incompatability with our network's load balancing and switched the clients' equipment.  I would still like to sort this out because we have many current and potential clients where DHCP capable outdooor access points that can control bandwidth on a per-device basis is fantastic.  We have even built marketing and delivery strategies around these capabilities.  Maybe it is related to a memory or hardware issue with the devices themselves that will be corrected?

I gave up and put UBNT AP's back up and took down the e400's. I am still using them in a couple places where I only need 5 GHz radios to work.


@tropicotto wrote:

I never found a solution to nor source of the problem and grudgingly ended up switching to UniFis at 4 locations (4 HotSpots and 1 E400 exhibiting the same behavior).  Clients who had very much regretted upgrading previously to the ePMP HotSpots are now very happy.  Before switching we did try using other HotSpots, and also tried replacing the HotSpots with E500's.  We also tried removing all the bells and whistles to make these as stupid as the UniFi's hoping for stability, but the same thing continued to happen.  With no solution found nor offerred, I wrote it off to some incompatability with our network's load balancing and switched the clients' equipment.  I would still like to sort this out because we have many current and potential clients where DHCP capable outdooor access points that can control bandwidth on a per-device basis is fantastic.  We have even built marketing and delivery strategies around these capabilities.  Maybe it is related to a memory or hardware issue with the devices themselves that will be corrected?


the ePMP1000 Hotspot is a single radio device with lower memory than the E500, but the connectivity issues you are seeing are unlikely to be platform related on the E500 (& in many of these cases we are seeing the 5GHz radio works ok). So far we believe this interop issue is limited to devices connecting in 2.4GHz mode; we have been having trouble recreating this consistently in the lab, hence the delay in resolution, but we do want to get this fixed asap.

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@bipbaep wrote:

Still no feedback from Cambium on this?! If you want us to swap UniFi with cnPilot, this is a very essential thing that just _got to work_...


Will reach out off-the-list to gather more details in helping us get to a fix.

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Could you solve the problem? I have the same problem with e400 / e500, when the number of users exceeds 40, users lose their connection to the internet, or to the AP or simply do not get an IP. Any cambium solution?

Hi Pablo,

What is the firmware version is running on the AP, 3.7.1-r4 is new image. We have addressed client connetivity issue, if not tried 3.7.1-r4 we request share your feedback and experience with new image. 

WIth Regards,

Channareddy