Force 425's are unstable

I have two Force400 series links and they both drop every few days. There’s no interference as in middle of nowhere and capacity is great. They actually perform very well, but then drop for no reason. “STA initiated disconnect…” it says, at both ends.

I run 80Mhz channels and MCS is 9 both ways on one link and 11 on the other. Both set to low latency. Been on 5.3 for a year and when upgraded to 5.4.1 yesterday MCS dropped from 11 to 7, yay.

I waited for over a year for fw to go from 5.3 to 5.4.1 and it seems to be no good.

Come on Cambium, you can do it!


Do you hold an STA? Do you have the option to change frequencies?

We have a few e4k 5GHz and 6GHz PtP’s… all of them have been very stable, no drops, no issues. All of them are running 5.4.1, or 5.6 betas and ePTP mode. We’ve tested low latency, balanced, and high throughput modes and they all seem to work as intended. Most of our links are 20 or 40MHz, although we have temporarily tested 80 and 160MHz on some 6GHz links, again without issue. We typically turn off/disable anything that isn’t needed. MTU set to 1700. QoS disabled. Both radios are not handling any VLAN’s directly, just simple bridge mode w/static IP’s.

I’d encourage you to reach out to Cambium and share your link details and they might possibly give you a 5.6 beta to try, although that’s more for testing TDD mode.

Thanks for your reply. I think these are different radios. I’m talking about the F400C and F425 in ePTP mode with 80MHz channels. 40MHz does the same on the F400C.

I have opened a ticket and will let you know how I get on.


Actually, I am talking about those radios… F400c, F425, and F4600c. There are a LOT of operators that are running these radios in PtP mode in the field 24x7 without issue. There must be some specific traffic patterns or something specific to your deployment that is causing these issues. It’s very important that you report these issues to Cambium and give them accurate information so they can help resolve the issues.

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Thanks for your reply. There’s also others that experience the exact same issues that I do, right here in the forums. Saying there’s a “LOT” of people running these radios without an issue is possibly the least helpful thing anyone can say when trying to help someone that is experiencing an issue. I have opened tickets as I said in my last post.
The issue will be caused by the firmware, just like every other issue i’ve had with Cambium radios in the past 4 years - there’s not been a single occasion where it wasn’t either a hardware or firmware fault, not one. Which is fine, so long as it gets resolved.

Well… notice how no one has responded to this thread confirming the exact same issues you’ve noticed? I interact with a lot of operators here, on FB, WISPAPALOOZA, etc using this equipment… what you’re reporting is not normal or widespread behavior for these radios. If it was, then there would be droves of people reporting these issues. Like I said, there has to be something specific to your deployment that is triggering these issues.

I have experience and reported both the AP TX sticking at MCS 0 and the station dropping for absolutely no reason issues in various threads, I think I’ve even started one or two about the issues. I’ve sent support files to @Fedor in the past as well.

So far, I continue to see both issues. Some links are more prone to them than others, but there is no clear pattern. The usual answer of “it’s noise” rarely seems to be proven by spectrum analysis. Both issues go away when I use another brand’s radio.

I could be more vocal about both issues (and more) and open a ton of tickets with Cambium, but ultimately I am only willing to spend so much time on it.

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I had a same issue with F425 ptp previsouly as well of dropping links from time to time.
then what I found is once I have changed my router from RB2011 to CCR1009, it works again with no drop.

80Mhz was dropping constantly. so I avoid to use, only runs on 40 now.

don’t know if this help, but just saying my experiences with F425.

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Thanks Jacob, it’s useful to know others have the same issue. It worries me to think they’ve known about it for this long and it still hasn’t been resolved. I’d only put one link in place as a failover for a 2Gb Siklu link, so it’s not a big deal when it faults. But, I have boxes of new F425’s waiting for the firmware to become reliable, and it’s been a year already. I did put one of the F425 links up but it drops every few days. No MCS issue but not stable :confused:

Thanks ntcc. That’s a very strange issue you had dude.
I have to run 80Mhz channel on the F425. The F400C link that has the MCS bug is only 40Mhz.

Funny you mention Siklu - the first time I experienced the TX rate bug was on a link that acted as failover to an EH-2500fx. The rates had been stuck for at least the full 7 days of cnMaestro’s graphs, but since it was a failover it was never noticed - Until it failed over and the failover wasn’t able to carry any real traffic.

I saw that, but think its a coincidence. The Siklus are up at 70/80ghz right, so interference cant be involved. How are yours powered? AP end of mine is poe from siklu and sm end is 48v DC powered. TheF425 links dont seem to do this so far, they just drop every 2-6 days, dumping my customers calls etc : /

Same Here, I have some F400 links connectorized and integrated. No issues at all. after upgrading to the last firmware this week, the latency on these PtP links came down to 2ms. Very good devices. Your issue must be some isolated case.


It’s an unfortunate fact of life that people are unlikely to post on a forum like this when everything is working fine (so thank you @dimas_j_perez and @Eric_Ozrelic for balancing the discussion)

This doesn’t lessen the importance of the issues that people are experiencing: if these devices are unstable for you, you absolutely should report it. It helps us to improve the product, and it helps other people who may be in the same situation to know that they are not alone.


In this case, both ends are powered from a netonix switch. In almost all other force 4xx cases I have both ends are powered from a netonix switch as well. I don’t believe there is any power issue.

We have over 20 PtP F425 links ranging from 2 - 9 miles and most in very noisy areas. Occasionally, throughput drops dramatically due to strong interferer jumping on the channel. Changing channels fixes this. Other than that, we’ve not had any issues whatsoever, and some of these links have been running 2 years. Various power sources including PoE brick, Mikrotik switch, Packetflux PoE. Most are on 40M channels with a few on 20M. The first few links we put in replaced Force 200s, AF5X, and B5. Throughput increased 50% to 300% on the same channel. I wish the 4500 we tested worked as well in the noise.


Have you tried WLR mode instead of ePTP mode?

Thank you for the info 3-d. I take it there’s none running 80mhz channels?
My F425s on 40Mhz and drop eevery few days. The F400C on 80Mhz and get the MCS bug, and also self reboot rarely.


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I have not tried that mode. Does it effect latency?

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