PMP450x Release 21.1 is now available

@ahults thanks for posting this. I’m sorry to hear about 21.1 giving this error.

Overnight we had one more customer report the same thing. They downgraded to 21.0 and the error went away. We are looking into it and will get back to you with more info.

I had the same thing, I also have the support file during the error. After several reboots the unit returned to normal.

@jnovak, would you be able to get the field_diags file from this unit?

Hi Lena,

I just pulled the ‘tech support’ file from cnMaestro. If that can be of help, let me know. This was ‘during’ the error.



Hi @jnovak, the tech support file cnMaestro would not have the history of when the issue happened. If you could help get the field_diags that would be best. From AP UI, type: http:///<IP_ADDRESS>/field_diags.cgi, then, download the *.gz file and send to us.

I have it, is it safe to upload this to the forum?

Hi @jnovak, if you have not already opened a support ticket, could you open one and upload it to this ticket? If that might be better that way.



I’ve got it sent over. Thanks!

Does this mean that the 40/30MHz channel width in combination with 5ms timing slowness has been resolved? or does Cambium still recommend using 2.5ms timing for 30 and 40 MHz channel widths?

No, that has not been resolved… that will take a very large overhaul. And yes, if you’re running 30 or 40MHz channel widths, 2.5ms frames is preferred. I think the only reason they’re recommending 5ms at this point is if you need LTE sync compatibility on their 3GHz radios.

I thought the 5ms was only an issue with 40MHz channels. Is it an issue with 30MHz channels as well?

Yes, please see this post:


I am running 21.1 on a 5Ghz production Medusa feeding my own home.
20Mhz, 5ms, 9 SMs total on this unit, downlink 75%, control slots at 6
SFP fiber fed data port
SM side is a new RETRO SM on a reflector
8./7 B on the downlink and 8/8 B on the uplink
Getting a little over 60 on a link test - full flood
My PPPoE session from the router barely crosses 30Mbps now whereas before it seemed in line with the link test

This 450m problem has been fixed by BETA-1:

I installed Beta-1 on one of our AP’s last night. I had to roll it back to 21.0 this morning due to poor throughput and high uplink frame rate maxing out at 100%. I have the field diags that I can submit.

@ahults, please help upload the field_diags log your existing support ticket #310015.


in what band? 3.5? 5?

Just upgraded to V21, had a large storm, and 450SMs stopped reporting S/N readings when they re-aquired…Had to reboot them plus some of the AP’s also stopped logging the upstream S/N readings so reboot of the affected AP’s was also required. Never have seen this before with earlier versions of firmware. Is this something new in V21 or has it been seen by others?

4 posts were split to a new topic: First generation 450 SMs losing authentication settings on 21.1 STA-1

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