PTP 550 5km link

Hi all, I have a 5km link that pushed a lot more bandwidth when I first set it up and I am not sure why… software changes? Here are some stats from the master and slave…




Running 4.5.4

Getting 254mbps DL and 69mbps UL 323mbps aggregate

I have 2 other links, one is a 25km link and the other is 32km… they are getting 220mbps… so I was curious my 5km link isnt getting more bandwidth?

Anyone? These ptp 550s are underperforming in my opinion, and for the price… double ouch

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If you do a path analysis in linkplanner do the signal numbers match up? I always start with a baseline and make sure I am getting the signal I am supposed to. By looking at your numbers I would say you are spot on, but I would want a sanity check before I went further.

Are these integrated units?

Sorry - I’d love to help more, but we’ve pulled all ours down and replaced them.

That being said - I can still probably give some pointers to try to help out… I left one PTP550 up (1.4km link) just for testing, so I can log into it and try things to try and brainstorm and try to help you out. :slight_smile:

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@ninedd, thank you. I just assumed that at this distance and the stats I have I would be able to get more throughput on a single 40mhz channel… but if this is all its capable of then I am fine with that…out of curiosity what did you replace your 550s with?

@DigitalMan2020 - I don’t think we never really had results to much different than yours. I was searching the forums to see if I had posed some results… I don’t really remember exactly offhand what throughput was.

But in summary, there was no good solution I could find.

  • TDD mode, the latency is too high for a critical PTP
  • ePTP mode latency is still much higher with more jitter than 1000/2000 series
  • ePTP mode isn’t compatible with F200 or F300 ePTP mode
  • TDD modes isn’t compatible with F200 or F300 TDD mode
  • ePMP mode doesn’t work in bonding, so it’s a choice between latency vs throughput.
  • No full-duplex mode
  • No way to configure, reset, test, optimize one of the radio pairs at a time
    without tearing down both radios and totally disrupting client traffic.

To answer your question: I replaced them with either:

  • Force 300csm in TDD mode in a few places with modest throughput / latency requirements,
  • in most places where we need higher throughput and flatter latency,
    I replaced the PTP550s all with AF5xHD

Hello Sir,

check on the sourounding if you do not see many radios in 5 GHz band.

Maybe the 25 and 32 Km are in rural area without much interference. If your installed is on a very busy tower/spot with a lot of 5 GHz radios, between choose narrow channels or use licensed radios (18 GHz band on the PTP 820S for example).

Review your environment.

Sincerely yours,


DigitalMan2020; The maximum TCP throughput we could achieve under LAB conditions was 330Mb/s regardless of configuration. UDP throughput is much higher. The high speed results shown by Cambium’s PTP550 product test are for UDP - they just don’t say that. I have removed all PTP550’s from service and won’t be using them again until the TCP throughput is >1Gb/s.

Hi, thank you for your reply… yes they do match up with link planner but in link planner I added some frequency interference… but as you can see by my stats I have little interference. When we first launched this link I was getting 330mbps down and 80mbps up, 40mhz channel, only thing has changed is firmware… original firmware was 4.4.3… I was considering rolling back… only reason to upgrade firmware was to use eptp, which was and is a complete disappoint.

@gregn, thank you for your reply… ya unfortunately alot of people have said they have pulled these out of production… but I do not have that option, being a new wisp and investing in the 550 because of the great features/performance that was being portrayed… but in real world deployment it seems to be the opposite.

@ninedd I truly appreciate all your input and replies! Thank you for the info and I may truly need to switch the Air Fibers… when I can spend the capital lol… so what kind of throughput/latency are you getting on your links? Would you mind sharing your results and what distance those Air Fiber links are?

Hi DigitalMan. I’ll get scolded again if I answer that.

Totally understand… free speech right! lol… k

I don’t think there’s any objection to reasonable discussion about technical aspects, even of competitor’s products.

@Olympe, Thank you for your response! As per my screen shots I cannot see this being a frequency issue. But I am open to correction.

Hello Sir,

as you said you were getting “…254mbps DL and 69mbps UL 323mbps aggregate…”, this is quite not well balanced for such a link.
In my personal experience with radios in the 5 GHz in city/town deployment, I usually consider my sourounding environment even tough when the noise is not apparent in statistics whenever I use a 5 GHz. Usually, Wireless ISPs tend to use the same towers with good and large coverage for access (point to multipoint) and backhauling (Point to point). That is why I asked you about the sourounding environment. Be precise on this so that we have a view of the space you are operating in. Otherwise, try out a licensed radio above 10 GHz if you stick on the 5 GHz.

Sincerely yours,

Niragira Olympe

I believe he said he is running TDD with 75%/25% ratio - so more DL than UP capacity would be expected in TDD mode.

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@ninedd @Olympe

Correct I am using 75/25 TDD PtP

I know we all are running after interference is the issue here but it’s not… I had been on a previous channel and my throughput was bad and in the MCS for UL and DL were modulating poorly, I am modulating at 100% DS 9 on DL and 94% DS 9 in a light to moderately noisy environment.

Hello Sir,

how is the performance now?

Sincerely yours,


@Olympe Performance is exactly as it was when I posted screenshots at the beginning of the thread… from most responses in this thread I can see that many are disappointed in the overall performance of the 550, I am also in that camp. I can’t believe how little can be pushed through at a 5km link with very little interference and the price for these units based on performance is truly mismatched. A lot of individuals have gone back to ubiquiti Air Fibers and Im not too far from that either.