Force 425 AP TX rate "sticking" at low rate

A number of times now I have seen an issue where for some unknown reason, the AP TX rate on a force 425 link will drop and “stick” at some arbitrarily low rate. An example from today is that I logged into one of the links and noticed the AP TX rate was stuck at SS5. Last week on a different link, the AP TX rate was stuck at SS0. On both of these links the channel in use is quite clean, according to the spectrum analyzer.

The “fix” is to kick the station and when it re-associates, the rates resume at their normal high numbers for some time. In the case of these two links that would be DS9 in both directions on one, and DS11 in both directions on the other.

Is this behavior one that has been addressed by AXG-4475 in the new beta? All of my links are running 5.1.3 currently.

7 day view of one of these links:

Last 6 hours of same link. You can see when I kicked the station and it came back:

I should clarify that most of the links I’ve seen this on are fairly low traffic. The one pictured above is essentially idle most of the time, acting as a backup to a Siklu 80Ghz link.

I have seen this behavior though on one link that averages ~100Mbps of traffic in the evenings.

We see this as well. Only solution is a reboot.

It is definitely not AXG-4475.
@Jacob_Turner Could you PM me tech supports right after you observe the issue?

I’ve PM’d you the tech support files from both sides of this link. Both were taken just before I made this post.


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i have the same issue with Force 425 and reboots haven’t fix it!! any idea ???

What version firmware are you running?
Have you tried the latest 5.3-RC21 firmware?

Version 5.1.3
I will try FW 5.3-RC21


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The Same after update

With 5.3-RC21 there are different rate algorithms (High Throughput, Balanced, Low Latency) that can be set on the Master side.

Does switching that up or down either way make any difference? We don’t see this ‘rate sticking’ ourselves, but I thought maybe if you tried the three difference algorithms, just to see if they make any difference?

What happened with this? I’m still seeing it on a F400C link. My F425 links are dropping every few days too. Horrible!

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I’m not sure if anything ever happened. The links we saw this on in the past we either still see it on, or they have been replaced with another manufacturer’s gear.

I have one remaining force 425 link that moves a ton of traffic, except when it disconnects once every few weeks for no real reason and then re-connects. I’ve been seeing a similar issue on epmp 4500 and 4600 gear. I’m more accepting of the issue on customer links as it isn’t a regular interruption. I have zero tolerance for it on backhauls though.

I’m confident that Cambium will figure it out. Until then though, these radios make ok customer CPE devices.

I AM using this link as a backhaul as there’s no noise and can get 800Mbps across it. I set biweekly reboots to try make the drops happen 4am instead of during peak times. It’s not cool that after a whole year these radios still cant maintain service for more than 6 days without disconnecting.

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@riddle, could you PM tech support file when it is in progress on 5.4.1?

Hi Andrii, I updated the F400C link to 5.4.1 and modulation immediately dropped from DS11 DL / DS7 UL to DS7 DL / DS 6 UL. This was not acceptable so I reverted the SM back to 5.3 and modulation returned to normal again. I left this link with AP on 5.4.1 and SM on 5.3 and it has been stable now for 12 days. This is one of the longest uptimes I have seen on this link so I am leaving it like this for now. I will update you again soon. Thank you

I’ve had this issue crop up twice on a 28km Force 400C link since installing it a year or so ago. It’s a very sporadic thing, but seemed to happen shortly after a dip in signal in both cases, and it was locked to the lowest SS0 modulation level after it until a reboot of the remote side.

I had ticket 357159 open back in June with attached tech support dumps, and the action was to upgrade it to 5.4.1-RC7.