Ethernet link down

we are having some problems with B24 Ethernet. The port goes up and down withoud any specific reason, On One side we have a Mikrotik CCR (original poe) problem is present on this side - other side of the radio link an UBNT Switch (original poe), eth problem is present at this side too. Running last firmware on both. Any solution to this? Will attach some logs…


SIDE A and SIDE B images

It looks like your radios are going through their normal boot up process for most of the “ethernet link down” log events, as you might note, most are right after the power comes on.

That doesn’t mean all of them are that way though, just most.

Out of curiosity, do you have “Rapid Port Shutdown” enabled under Preferences >> Management >> Miscellaneous? While you are there, how about Flow Control?

If neither of those are enabled, it could be an issue with the PoE adapters, could also be bad cables. (I would lean towards one of these two options) I would check those, then in that case the options for where the issue could be will start to get slim. Is either location nearby a strong transmitter specifically in the FM range? Maybe some other high power something or another (Like huge motors or A/C units)

Dear William,
thank you for your answer. Rapid Port shutdown is off. On Mikrotik CCR flow control is on. PoE are new, shipped last week. No other disconnections anyway on last 2 days.
What are preferred settings for FlowControl and Rapid Port Shutdow?


Flow control is supposed to be useful, but I always turn it off because we had issues with it and UBNT radios a few years ago. I have never gotten around to testing it with Mimosa Radios.

Rapid Port Shutdown could be your issue, it’s job is to indicate to the router/switch that the radio is plugged into that the wireless link has degraded below a threshold (or in Mimosa’s case when the wireless link has completely disassociated)

A more full description of the two features can be found here:

Have seen this for years on B5’s. Typical if I power it with a Netonix the flapping mysterious goes away. The flapping will also happen if using a POE and the plugging into the Mikrotik. Something about these two brands that don’t always like each other.

Now we have several that never flap, I cannot see any difference in the installation. We have changed cable, POE, routerboard to other models or chipsets and the only thing that works is changing to Netonix for us. Might try running fiber up to the radio and simply powering it with a POE. You can get UBNT fiber premade and cheap.