B5 ethernet bouncing up and down


We have several models of the routers you have in our own outdoor test network, and found that there are certain firmware versions (theirs) that are compatible, and others that are not.

We’ve updated our firmware several times to adapt to various 3rd-party routers, and have even gone so far as to expose autonegotiation controls for troubleshooting rather than introducing additional logic for specific vendors and all of their firmware versions. You can see how this would be moving target.

In some cases, the other company’s hardware or firmware just isn’t compatible for one reason or another, and for practical reasons, the switch addition is the shortest path to address the problem. It can resolve clock timing contention issues, and provide isolation - either logical or electrical in some cases.

In @Bryan’s case, he found a great way to add functionality. Nice! Our experience with Netonix switches has been positive as well.



Does the B5c and the A5c use the same physical components and software code for the ethernet?

The reason I ask is we have total of 4 mimosa products at this site, All of them are connected in the same manor and to the same Mikrotik. Yet the A5c is the only one that has the issue. I have 7 other B5c radios in my network and none have this issue. I have a hard time with the idea that it is something to do with firmware and or hardware combination when i have others that are working fine, Unless it is something to do with the A5c itself.

The 1100ah is standard kit in our network, we have one at every tower site and most business customer sites. The guy who wrights the checks is going to poop a cinder block when I tell him we will need to buy a netonix to put behind every 1100ah if we want to move forward with the mimosa roll out. Not to mention that will introduce yet another step to teach the support engineers to work with.

Also after my horrible night about a year ago when i had to drive across three parishes resetting Mimosa radios that flaked out after upgrading, we have moved over to web controlled relays that are connected to the PoE injectors. This setup is a god send we have saved so much money on digital loggers as when a PoE injector bites the dust its a lot cheaper to replace a single injector than a Digital Logger. The web relay gives us one interface to control every thing from radios to flood lighting! Going back to a midspan setup would be a step backwards at this point.


I am about to start a testing project on this, It seams some other Mikrotik users have had similar issues with a few other products. I guess we have just been lucky in the past.

I am going to run through the paces of back dating the firmware and even try to install a third party firmware on the hardware. i will try some different forms of isolation and eventually swap out all of the electrolytic capacitors on the Mikrotik board as one Mikrotik user has suggested.

I am going to make supp-out files for Mikrotik, @Chris does Mimosa have a way to export data from the radio I can export files for you guys also!


Hi Samuel,

The A5, B5, and B11 all have different Ethernet chip sets. A5 has an NPU, and B11 has an SFP, so these differences drove the change.

For Support files, go to Diagnostics > Logs > Support Info > click the blue Support Files button to download a .tar file from each radio to your local computer, and then email the files to support@mimosa.co.

Interested to hear what you find in the router experiments.


Mimosa B11 and B5c having issues staying up on variety of Cisco Routers as well. While the radio side is awesome there are way too many issues on the Ethernet side. We are asking ourselves if Mimosa is really ready for prime time? We do not have these ongoing issues with Cambium or Ubiquiti, they just work.


After reading other users experience and fixes, I decided to replace the power injectors. Problem stopped and has not showed up again. This was last week and everything works good now.

2 X B5 link - 1.5 Miles.
Cisco SG200 switches both ends. (Non POE)
New power injectors = Ubiquity POE-48-24W-G
Access point cable = 300’ Cat6 shielded.
Station end = 100’ Cat6 Shielded.

Before changing power injectors.

After changing power injectors.

I will keep monitoring and hope the problem is fixed.


Mats, I’m glad that works for you. The part that is confusing me is the power supplies I originally got show +56V on pins 3456 and ground on pins 1278. This pinout is not 802.3at compliant where the pinouts are 1236 and 4578. I looked at the Mimosa Specs for both radio models and they say they are 802.3at compliant. Perhaps this has been my issue all along? Somebody from Mimosa want to straighten me out on this PLEASE?



I was reading somewhere that both configurations can be used since Mimosa is using diode bridges for the power.

Just checked my logs, and no new entry or problems.

Here is Mimosa trouble shooting:

Port Flapping (alternating between Link Down and Link Up)

Repeated link down and link up messages in the Event Log (Diagnostics > Logs > Events) indicate a power or cabling problem.

Example Event Log Messages
MIMO_EVENT ethernet link down
MIMO_EVENT ethernet link up (1000/Full)
MIMO_EVENT ethernet link down
MIMO_EVENT ethernet link up (1000/Full)

Troubleshooting Steps:
Ensure that the AC cable is secure at the PoE and AC outlet. If AC power fluctuations are expected, install a UPS with power conditioning to ensure a clean source of power to the PoE.
Ensure that high quality shielded CAT6 cable is installed between the Mimosa PoE and Mimosa radio, and that the total cable length is 100 meters (328 feet) or less. Test continuity of the cable with an Ethernet cable tester.
If possible, replace the PoE Injector in order to determine if the port flapping issue is with the Radio or the PoE Injector.


Yes, a tech, David Dippon, gave me this link:


I was concerned about smoking an expensive radio! I’m going to try the ubnt poe.



Please report back with result after changing POE Adapters.


you did this with B5’s not B5c’s, correct?


I did it with B5’s, but same applies to B5c.


I’m having same problem with 2 B5c and 1 Original Mimosa B5c PoE Injector (first side) and Ubnt 48V PoE Injector (other side) because after only 3 days the original Mimosa PoE was broken causing radio continuosly reboot.

On the first side, the cable is only 40 meters long, UTP outdoor cable (Max Cable). Tested and working cable. Problem ethernet flapping.

On the Ubnt PoE side, I have same problem. In this case the cable is 60 meters FTP outdoor shielded cable. Tested and working. Problem ethernet flapping.

What I need to do to troubleshoot ?

PS: in a test environment I have used a Netonix Wisp switch without problem.


After replacing the POE injectors I noticed one more positive thing.

One of my B5’s rebooted every time we got rain. The log showed that it was power cycling causing the reboot.
I have not had that issue a single time since replacing the POE injectors, and no more flapping ethernet.

All is good now.


I Would like to share my experience.

2 B5c directly connected with mimosa poe brick to mikrotik RB 1100 AHx2 both ends.

Ethernet flapping as described by others.

I only turned on Ethernet Flow Control in Management menu, both sides, and problem disappeared.

No other modify. Reading on web, the other thing to do is force autonegotiations to off on mikrotik choosing right speed and duplex combination. For me I haven’t done this other change.

I hope it will be useful to others.


I had tested few different brand poe injector, the finding is…
only this model work with no issue:

not to trust how mimosa guide u to replace ur cable, as my fact finding with live on SFTP Cat5, SFTP Cat6, SFTP Cat 6a, all useless cause the port flapping still happened.

but, once u replace with pd-9001gr-ac poe, everything in good condition.


Hi Dave,

We have the same problem. We have more than 90 B5 units with continuous ethernet drops.
We are desperate.
The cable is cat6 FTP certified.
We use mimosa PoE injectors.
We connect the antennas to sw CISCO Catalys.
We update firmware to 1.4.5 with ethernet interface in ManualSlave mode, but the problem continues.
Could you check your logs to see if the problems after changing PoE to another model solves the problem?
thank you very much


Hi. I have the same problem with products B5 and B5c. I think the problem is in the firmware or GPS module, when i connect the mimosa B5 or B5c to PoE with standart IEEE 802.3af or IEEE 802.3at from mimosa or other manufacturer, the mimosa eth link UPs 1000Mb/s Full Duplex while the Power led of B5 or B5c is blinking.

I have observed that the startup of the mimosa devices always follows the following steps:

  1. When you plug the device to PoE: Link UP 1000Mb/s Full Duplex
  2. After a few secods: Link down
  3. Again after a few seconds: Link UP 1000Mb/s Full Duplex
  4. After a few secods: Link down
  5. And finish, the Power LED stops blinking: The device negotiate ethernet.

Testing in my office with an cable with 35 meters long ( Cat 5 ), plugin the B5 unit to a Gigabit Passive PoE, the device negotiate 1000Mb/s Full Duplex and no link downs…

Testing with same equipment with the mimosa B5 unit in a telecom tower, the device negotiate 100Mb/s Full Duplex and eth link down all the time…

But… If i test the B5 unit on the floor with same equipment, negotiate 1000Mb/s Full Duplex with no link downs.

I test to run the B5 device with Cat6 cable, Cat5, mimosa PoE, Unifi Carrier PoE but the result with the mimosa unit in the tower is always eth 100Mb/s Full Duplex and link downs all the time.

I have had similar experiences with B5c, but I have never had this problem with B5-Lite units…

From this reason, i think the problem is definitely not in the cable, PoE or router. The problem is in the Mimosa B5 and B5c units and probably in the firmware or GPS module.

My Mimosa devices uses the lastest mimosa firmware, today 1.4.6 and the mimosa B5-Lite no have any problems but the mimosa B5 or B5c i cannot practically use them with the problem with ethernet link.


Update and problem solved.

I replaced one B5 after a lightning hit, and the new unit was terrible regarding flapping ethernet.
Replaced POE adapter with a UBNT unit as recommended by Mimosa. A little better but still a lot of flapping.

My cable is 95 meters - CAT6 Shielded and everything grounded.
Switch was Cisco SG200. Tested with Netgear and generic Gb switch, but it did not help.

I was reading through other post and it was mentioned that Netonix switch works, so I ordered the 8 port Netonix.
Have been running on new switch for one week, and not a single problem. I even tested running with power on 2 cable pairs and it is still perfectly stable.

Switch is expensive, but cheaper than replacing the B5 with another brand radio.

Old switch

New Switch.


Problem is BACK.

Looked good for a week, then the flapping started again. Link down - up every 2 minutes.

Ready to replace with something that WORKS.
I am sick of all these problems.