PtP550, F300 series, F400 series ePtP mode unreliable

I bought the ePMP3000 the day it came out and I love it. What I don’t love is these radios in ptp mode - they simply aren’t reliable, still. I thought 4.7 had finally fixed it as I saw some long uptimes, and this was my main gripe, but now i’m seeing this MCS fault, where one direction drops to MCS DS0 or lower and is stuck there until a reboot.

My wisp is small, with currently 250 cambium radios, but I know them like the back of my hand, I feel like I know them better than many. And I can tell you, they drop, self reboot and have a modulation bug.

This post was going to be about how 4.7 fixed eptp mode, so I checked in on two random F300-25 links that service a handful of customers. One had an uptime of 2 days and the other had the modulation bug and UL MCS was stuck at 0. I rebooted the link and it went back to normal.

This is the story of cambium ptp for me - ‘reboot and everything goes back to normal’. It is very frustrating as there’s no acceptable reason for this to still be happening. I put my first F300 link in 4 years ago, and it would self reboot every week or less. Now 4 years later it’s still doing the same thing.

I now set my switches to bounce power every week, and might change that to twice every week. But this really is not good enough. I have a few UBNT links too and of course they sit there working forever, with no drops or bugs ever. So we know it’s possible. But I don’t want UBNT links, I want cambium links. My Siklu link does the same - it works forever with no faults ever.

I do love cambium because they gave us the epm3000, and the F300 series are stable when connected to them, it’s a beautiful thing. But the ptp550, F300 and F400 series in ptp mode have never worked properly and still don’t.

I have put other radios side-by-side next to these links to prove it’s not some weird interference, as that’s always the go-to cause, and they work fine.

Come on Cambium, please sort these issues out for us, we have waited long enough. We will support you into the future but you need to support us too.


Hello @riddle,

we are always glad to read our customers’ feedback! You help us to get better!

We take measures and react to every given feedback. Sometimes our reaction is confusing because we can not fix everything by fingers click. It is engineering, it takes time to retest, to isolate and to rework our code. Also it is CI/CD so we have a schedule and all works have to follow it.

Another thing is that 2 issues looking absolutely the same can have absolutely different root cause. From a SW bug to rotten cables on the mast. We have to check everything with a customer to find it.
It is really my challenge not to be biased by all previous bugs and to investigate each new situation from scratch.

4.7.0 had a lack of stability due to new heavy features. So we have issued with fixes. It looks very stable now.

If you have an exact issue you should raise a support ticket. A new one for each issue. There you will have a full tracking and updates until the resolution. We fix every issue met by our customers! There are no tickets left without a resolution. The best thing you can do to expedite the resolution is to make us aware of the issue.

Be patient to support’s questions! Experienced engineer always collect all the details. And sometimes it is not a bug but just a toasted radio. Sometimes Ethernet or FEM only is burned. It happens due to lightning, instalation mistakes etc.

Thsnks for your reply, Andrii.

I understand your points and will continue with the tickets i have open. I have tried and the same issue occured. I may already have support files and photos from it.

FYI i have mild ocd and this makes me do every installation perfect. Every mount, every alignment, every cable, every RJ45. I built all 13 broadcasts site on my own and did all 240 customer installs to. Ive not had help from anyone so i know every inch of the nw.

Im open to suggestions and am happy to be proven wrong. My only goal rn is to stabilize my f425 link so i can deploy the rest ot them.

I will update this post aling the way as it will help others.


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we dont use eptp (too many issues for us not related to the radios) but using TDD-PTP and have not issues with MCS getting stuck.
Have you tried switching to TDD-ptp?

We had some issues with the early F300 hardware and ended up ditching the F300 in favor of Airfiber 5XHD, which has been rock solid. We do still have one F300 CSM backhaul link that has been running solid for quite some time, in ePTP mode We found the F300 to be much more picky on good ethernet connection and grounding that the old ePMP 1000 series.
We recently deployed our first F400 CSM backhaul link, deciding to try it versus the AF5XHD and see if it worked as well as it was hyped. Initially had shades of the F300 start with a defective radio out of the box only operating on one chain. It was RMA’d and the pair has been running for well over a month now with no issues at all. DS11 at 10.4 miles, but only on a 20 Mhz channel. We will be switching it to a 40 Mhz this weekend and let it cook. Getting just over 200 meg both ways on 20 Mhz and we are actually pretty impressed with the F400 CSM so far. Performance has been very stable and if it remains stable, we will be replacing some old AF5X links with the F400 in the near future.


That’s the same for me. In the 1000/2000 series ePTP mode was magic, but when the 3000/300 came out, with its different (and incompatible) ePTP mode, it just never worked right for us. We tried everything, with very detailed testing and results, that went unresolved. We eventually stopped reporting it because we are getting nowhere.

So we switched to TDD PTP mode on our 3000/300 PTP links which of course theoretically decreased potential throughput, and increased base latency slightly - but for us, the throughput and latency at least became relatively stable in TDD mode.

So, for us in most locations, we don’t use ePTP mode anymore on 3000 series, only on 1000/2000 series.

I want to stick with Cambium because I know how well they can work. In fact, they are awesome. It’s just the bugs that hurt my wisp organ - when a customer’s call drops because of a firmware bug I despair. We work so hard to provide a good service so it gets frustrating. I will try to be patient and work through it with the techs :slight_smile:

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