Once I noticed problems with a link on different Mimosa B5.
The link rose and fell at 1000Mbps every 5-10 seconds, respectively, the customers had a degradation of traffic, pings fell out.
I will give an example of logs with D-Link to which the Mimosa B5 access point was connected:
68 2018-10-25, 09:55:49 Port 26 link up, 1000Mbps FULL duplex
67 2018-10-25, 09:55:41 Port 26 link down
66 2018-10-25, 09:55:39 Port 26 link up, 1000Mbps FULL duplex
65 2018-10-25, 09:55:36 Port 26 link down
64 2018-10-25, 09:55:31 Port 26 link up, 1000Mbps FULL duplex
63 2018-10-25, 09:55:27 Port 26 link down
62 2018-10-25, 09:55:20 Port 26 link up, 1000Mbps FULL duplex
61 2018-10-25, 09:55:13 Port 26 link down
When trying to set the port speed on the switch to 100Mbps (instead of 1000Mbps), the link became less likely to disappear, but it also disappeared about once an hour.
In my case, the problem was in a poor-quality cable, and I note that if you encounter a similar problem with a link falling, then it is most likely in the cable, and not in the Mimosa or switch settings to which it is connected.
The problem was observed on several devices, replacing the cable or reducing the length of the cable by lengthening the power cable solved the problem.
The “Autoneg Mode”, “Ethernet Speed” parameters on all Mimosa devices use “Auto”.