320 Cold Issues

I hope the community can help me with this one, because I'm really struggling and support doesn't seem to be able to get it resolved.

Some of the 320 equipment has been misbehaving when it gets cold.  The problem lies with both the APs and SMs, though we've been able to diagnose which APs were defective and get them RMA'd.  You can FTP into the APs, and send them into support to be analyzed.

The SMs are what are really giving me headaches.  There's no way to tell which SMs are affected other than the customer complaining about the link randomly dropping or running very slowly in cold weather.  There's no set temperature either, some customers have problems below 0C, others are fine until it hits -20C.

I am replacing supposedly defective SMs with brand new ones straight out of the box, and the new ones exhibit the same problem.  I'm going to have to go out today to replace a unit again because the second brand new replacement SM is also defective.

I know that there is a way to test this, because I sent in a bunch of units in to Cambium to be tested when this happened last year.  I've tried duplicating a testing environment myself, but some of the radios that seem fine when I test them are failing in the field.  I know that traffic has to be passing through the SM to trigger the issue, and I know that the session to the AP doesn't go down when the link does, and I know that I'm not seeing a lot of ethernet errors in netstat, but I haven't found a way to combine that into a working test.  I've asked support for any information they can give me regarding how to test these SMs, and they haven't been able to help me.

Because I can't consistently test SMs, I can't tell which new ones are good, and I can't verify that the ones I take down are bad.  It's possible there is a common issue here, but I can't rule out the SMs to be sure of that.

I'm at my wits end here, and support is either unable to help me or too overworked to have the time.

Things have gotten significantly worse since the weather has gotten colder. We’re getting down to -30C now, and we’re having APs fail again. APs that we were sent to us under RMA for this issue last winter which were supposed to be known good and cold tested are failing. I am sending in crash logs to support, and I haven’t gotten a response since Dec. 9th. We’re losing customers in droves over this, and Cambium appears unable to do anything to address the issue.

That is very unfortunate. We've never had these issues but I've spoken to several other ISPs that did, and RMA with new hardware versions solved everything. Is it possible there's something installation-related that is the real cause of these failures?

How large is your PMP320 installation? I'm sure you're aware that it's now a dead platform and replacement hardware is going to be difficult to procure in the future.


Can you send me a message with your support case number?  Are these 3.5 GHz or 3.65 GHz APs?   How many APs are you experiencing this on?