PMP 450i 900 Modulation issue


We are currently having issues with at least 4\5 PMP 450i 900mhz AP's within our network having modulation drops i have had a support ticket with cambium open regarding the issue since  the 9th of July 2016 and now I'm not getting any response regarding the issue and the last response was on the 9th of October.

The ticket number is 102424

Just to fill everyone in on the issue we are experiencing an issue with the new PMP 450 equipment having large modulation drops every 6 to 48 hours where the AP with have 20+ SM's connected to it in 8x mode then as time passes the modulation will fall to 1x for all SM's and be stuck there till the AP is rebooted causing the AP to fall to a unusable data throughput. I have used the co-location tool

Cambium has had its engineers look at the cause of the issue with no resolve as yet so its not a configuration issue to my knowledge.

has anyone else been experiencing these issues?

I'll confirm and stand beside you. We are seeing something similar.

The issue appears to be worse as you place more clients on an AP.  We have an AP with 10 clients that need to reboot almost  daily.  When they do reboot, they run great for hours.  Another with 6 seems to last longer, but still requires reboots.  Those with only one or two clients are not showing symptions yet, but I've only been aware of the issue for a few days.

We start to notice client modulations dropping in random fassion, not neccessary every client at once, but eventually over time all of them are reduced, like a memory leak.  It's becoming a major problem for us and appologies are losing their effectiveness.

Today, I'm updating our worst case from 14.2 to 15.0.1.  I'll let you know if that helps.  Failing that, I'm wondering if I can improve the stablilty short-term by rebooting them nightly.  I'm really hoping the new firmware has a hidden fix however.

We are aware of an issue that affects 900 MHz sectors under certain conditions, and are working on a fix.

We will contact you guys having issues via PM or via a support ticket if you submit one.

If anyone else is experiencing these issues as well, please post or submit a ticket so we know, and can get you a private software load to test out the fix.

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we are also having this happen to one of our sectors.

we have 2 450i 900mhz colocated (not re-using frequency) synced with a ugps and only one of the sectors will drop all modulations for all of the clients at once... yesterday morning they were okay and i checked at the end of the afternoon and i had to reboot the ap to get the modulations back up.

As an update to the thread, the latest general release of 5.0.1 is not a fix.  After hearing from Matt, this is not a surprise.  We are added to the support ticket and are eagerly awaiting a fix.  We now have three sites identified with the issue and are having to reboot regularaly.

Any timeline on the fix or recommendations for a workaround?

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Our issue appears resolved.

Cambium provided me with 15.0.2(Build 28) to run on our AP.  I've been successfully running for 40 hours without issue.  All speeds remain stable.  I've deployed it to two other APs and they are also showing stable modulations for the past 17 hours..

Thank you to Matt and Dhaval for the quick turn-around on the firmware! I look forward to a general release.


Just as a follow up to this thread, we have released R15.0.2.1 as an official release.  The fix for this issue (specifically on 900 MHz) is in there, and this issue is resolved.

If you suspect you're being affected by this, please download at least R15.0.2.1 for your 900 MHz 450 radios.



Fantastic! We had been experiencing this too, although at a much slower rate than a day. I didn't realize this was already fixed!

Found mention in the 15.0.2 release notes. Just threw 15.0.3 on our two 900 MHz 450i sectors which had been running 14.1.1