B5-Lite: download speed 150 Mbps vs 500 Mbps at router

Hi all,

We have a setup with a Ubiquiti PoE-5 router and a B5-Lite set to transfer the internet over around 300 meters. At the router we have a bandwidth of 500 Mbps down and 50 Mbps up. On the B5-Lite 300 meters away we have a maximum download speed around 150 Mbps and 50 Mbps up. No other devices connected and laptop connected to the power / PoE switch of Mimosa. We have clear sight between the 2 B5-lite units and the signal quality is -46 DB.

We tried to align the set and this is the best we could get. As the max speed is 750 Mbps and the distance is not far, we expected at least 450 Mbps at the remote B5-Lite.

Any suggestions to test and to improve the speed are very welcome


Sounds like an interesting problem. I would start off with trying an iPerf test over the link so you can see what the maximum limits of the link are.

You might also try adjusting the window size/alotment (the ratio between Down and Upload time) to better optimize for your situation. (75/25 is probably where you want to be) This will help with your upload imbalance.

If that does not help could you post a picture of your Main Dashboard, Channel and Link settings? Sometimes the extra information is useful for getting us informed about your situation.

Thanks for the suggestions. I am on site again this Thursday and do some tests. Once I have the results I will post it here.

If there are suggestions and/or more things I should test, please let me know.

I’ve got a similar situation. We have a 400/400mbit/s service to one of our PoP’s. Using a B5-Lite linked to another building about 150 meters away we only get around 100 mbit/s in any direction. The signal quality is good (clear line of sight, -45db etc).

I didn’t check further as I only needed 50/50 over the link anyway, but I was a little disappointed.

Thanks for your reply Arron.

We are using the B5-Lite for 1 year now. Previously the available bandwidth from the provider was 200/20, so 150 Mbps seemed fine. Now the line has been upgraded to 500/50, so I expected it be at least 400 Mbps.

Let’s hope we can find what is causing this. Once we have, you can try out the same solution on your installation.

We use the B5-lite to support our student housing links… We have never had an issue with the links or their performance. In particular I have 2 links that are about the same distance as you are showing…300m.

I have a physical link of 867mb, and MAC speed of 520 both ways.

I am using 1x80 channel width.

Really, for all of our installs for the B5-lites, we initially use the auto-everything to let the device get the connections going initially on its own. We then do a monitoring of the radio to make sure we didn’t land in a populated or noisy channel. Once we’re happy with that, we simply change the channels to be static, taking off the auto-everything.

We leave the traffic split on auto, and so far we have not needed to change to specifically any other split.

On the Rate Adaptation, we found for our case that using EVM / Aggressive was the setting that gave us the best consistent rates.

We’ve have this particular location in place for over 2 years now with no issues whatsoever except when we had a firmware upgrade issue that required reloading multiple times before it would go cleanly.

Now — one other thing with ANY of the B5 series, is despite these being close, you still have to do an alignment.
I have a -34db signal between the radios, and other than VERY heavy rain (like the kind you can’t see across the street heavy), it’s never really moved at all.

I have found with these, and most other PTP 5ghz radios, JUST because you’re showing what appears to be a great connection initially, you MUST to a proper alignment. You can have a great visible connection when being off-center with the link because you’re so close it’s almost impossible to not get a good connection.

If you didn’t already do that, I would offer that you really should as it will make a difference. The beamwidth of the B5’s is only 8 deg, so there’s a huge room to miss your target, and with the proximity of these being at only 300m, it’s easy to get fooled by the reported numbers.

I hope some of this information helps solve your link rate to where it should be. Really, at that distance you should be showing a link that’s at or near the maximum 867mb depending on the bandwidth you chose.



we have a B5-lite 500m link also. Signal is around -51dBm. TDMA:auto, Bandwidth:80MHz on a clean frequency. Speedtest with mikrotik bandwidth UDP/1500 is 260/230 simultaneous. Internal bandwith test not works :frowning: .
my tips: try to decrase tx power to around -50. Choose clean frequency. Set TDMA to auto. Make sure you are linked at 1Gb on ethernet side.

best regards, Gabor

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Hi Bryan & Gabor,

thanks for your reply & info. As the set is at the beach and it was 9 Beaufort today, I skipped checking & testing the different suggestion for today. I will be at the site during the weekend and keep you posted of the results. I will also make screenshots to share.


Never heard of the Beaufort Scale before today, but after a quick search I do not envy you one bit. Good luck.

One more question; is there a difference in maximum speed depending on which B5-Lite is used as Station and which is used as Access Point? We have the Access Point at the router side and the AP at the ‘receiving’ side.

I don’t think so. It depends the radio enviroments, snr, noise, etc. In a clear frequency I have fully symmetric traffic (with auto tdma).

It will matter depending on your “Gender-Traffic Split” (See: http://backhaul.help.mimosa.co/backhaul-ug-tdma-configuration-b24)

As I suggested earlier, because you are very far away from symmetrical service I would recommend doing a 75/25 split. This should work out just fine because the AP side of the B5 Lite link is connected to your router and the Client is down stream. This way you are removing a moving part that could break in the future. (A philosophy I got from my father and has saved me a time or two.)

Thanks again. Hopefully I will have the results of the tests on Monday. Enjoy your weekend!

Hi @Nick5,

If you continue having issues with this link, please post screenshots of the Dashboard and Channel and Power page. I am more than willing to look at this link. If you want to PM me the serial numbers, I can go ahead and look at cloud stats now (if you have Cloud Management enabled.)

Also feel free to stop by chat anytime during the day and we can look at the link as well.

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Hi all! Thanks again for your replies and suggestions. I have been testing (most of) the suggestions last Sunday. Below a short summary of the results:

Tested with several TDMA settings and the EVM / Aggressive option. No option resulted in more available bandwidth.

Somehow, the PHY Tx/Rx seeems to have a limit of 173 / 173. We had the same last year. Because it is a setup for the beach, the installation is stored during the winter. So, after building up the installation, is is the same as last year.

We also tried several alignments, but this also showed no improvement.

The Tx Power is set to 10 dBm, which seems to be the minimum? We only have 2 options; 10 or 11 dBm.

Attached some screenshots of Dashboard & Channel & Power & Management. The is the B5-Lite at the router side. The is the one which is on the beach. We have 3 Ubiquiti Rocket M2 AP’s, all connected to a 1 Gbps switch with PoE.

Thanks again in advance for your help. If more information is needed, just let me know. I am on site again this Thursday evening.



173 is the maximum for a 20 MHz wide channel. The absolute maximum that everyone advertises is with the widest channel the device supports. To get the 500 Mbps you will have to use a wider channel. I did not think of this because many people are irresponsible and use the widest channel available no matter how much data they are passing (I have seen Towns put up 80 MHz wide channels for a SCADA system that was pushing less then 2 Mbps max. We adjusted it for them when we were doing other work in their system)

It looks like you have a pretty clean spectrum so rock it out, you should be able to make the change if you have remote access, just make sure you change the Client in the PTP first then the AP.

Exactly what @William5 has said here. You’re seeing great performance using a 20MHz channel! If you want to see 500Mbps, use an 80MHz channel. In the best case scenario (MCS9) and in auto mode, you can push over 700Mbps with this radio.

Thanks guys! It is often much more simple than you expect, just like this issue! I will try it Thursday and let you know the outcome (which you already know ;-)).

Just one more question; does it actually matter if you change this on the AP or the Station? Or is there only one option as the other follows the settings of the other?

It actually depends on your settings, http://backhaul.help.mimosa.co/backhaul-ug-channel-power-settings-b24.

If you have the Client set to “Auto Everything” or “From AP” then it will adjust with the AP and all you will have to do is change the settings on the AP.

Hi all,

Yesterday I tested with 40Mhz & 80Mhz, and also EVM & Agressive mode. This was very successful as we got a great improvement of the download speed.

We found out the 40Mhz with EVM & Aggressive mode seems to give the best result. We just did one test which resulted in 280 Mbps download and 50 Mbps upload speed, directly on the Mimosa. The signal was very stable at test on the Mimosa. With the 80Mhz the signal was a lot less stable, also on other channels.

I will do some more testing during the weekend. if there is anything I need to check / test, just let me know.

You have been a great help! Thanks a lot for your time and have a good weekend!

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