Multicast issues

So just last week we put in a ePMP 1000 I have upgraded to the latest firmware of 2.3.3 Internet traffic seems to work fine. However we are having major issues with Multicast. One stream seems to work ok most the time with minimal break up / freezing. If we turn on a second STB we have issues with freezing picture and break up. We are only about 2 miles away from the AP , and only one SM. We have a RSSI of about -57 up and down and SNR is mid to high 30’s. I have tried the multicast priority , setting up a QOS for all the STB’s , and several other things in hope to improve this , but no change. It seems when the multicast traffic hits about 15meg aprox it will start having freezing. However if you do a through put test it will get 190meg connection both ways ( 75/25 download/upload priority) Is this the limit of the device or is there some other settings I should be adjusting?

So after using Flexible ratio now, it will do up to 2 streams , but no more then that.

Shouldn't this equipment be capable of more than this?


Have you gone to Configuration -> Network -> Broadcast/Multicast Traffic Shaping -> Reliable Multicast and set this radio button to "Enable"?


Yes I have. Not much difference with it.

Any other ideas?

Sorry we haven't been able to get a response out to you sooner. We are actually investigating this issue and at a high level it seems like your mulicast is going over the lowest modulation. We will confirm within a few days and get back to you with urgency.

Sorry for the delay.



We have tried to reproduce your issue in the lab.  Here is our results:

fw: release-2.3.3
mode: 75/25 and flexible
Multicast streams: 5 (overall load ~ 80 MBps)
Broadcast Storm control: 100 pps (for SM/AP)

in case of 20 Mhz on 75/25 with Reliable Multicast OFF
DL Multicast throughput ~ 7.5 MBps

in case of 20 Mhz on flexible with Reliable Multicast OFF
DL Multicast throughput ~ 10.5 MBps

in case of 40 Mhz on 75/25 with Reliable Multicast OFF
DL Multicast throughput ~ 15 MBps

in case of 40 Mhz on flexible with Reliable Multicast OFF
DL Multicast throughput ~ 20.8 MBps

in case of 20/40 on 75/25 and flexible with Reliable Multicast ON
DL Multicast throughput ~ 80 MBps without losses

As you can see the feature is working well for us on our lab set up.

We would like to continue to work with you to help you solve the problem you are experiencing with your deployment.  Could you contact customer support via the URL provided at:

This will provide someone to actively support you.


Just reading this post and it appears to be exactly the same issue we have been having for over 6 months.

When talking to Cambium they report that it test fine however,  when you try to run multiple streams in a real world situation is falls on it's butt.

We are only a mile apart in a rural area with true sight between the units.  First STB works fine, second is ok most of the time.  Third causes freezing of screens much of the time.  Bandwidth shows to be about 100 Mbps. whenever we test and Internet traffic has always been good.  The problem seems to be in how the epmp deals (or doesn't deal) with multicast.


Hi Valunet,

Can you please check that "Reliable Multicast" is turned "On"(default is "Off") under Configuration->Network on the AP side?