Got no answer to this so nobody has the problem (or noticed it). I've exchanged the SM and now the problem is gone.
So it has to be a hardware fault at the wireless part of the SM which causes disconnects under load. There is no other sign (low signal) that gives a hint to a problem. It just drops the connection when there is bulk traffic for a while (20-60s) and reconnects after this. >How does ePMP work for you? >We've a testsite with ePMP connected to a UBNT Omni and only one CPE connected. >(LOS -70db signal due to distance). >We've had disconnects due to false Radar Detects with older FW. >Now we have disconnects when pushing a lot of Traffic for a short period of >time. > >CPE Disconnects, does channel clear detection and then reconnects. > >At this tower we've free channels. Tested with all possible settings. >Cambium support do tests for weeks now and do not come to a solution. > >Is this a special problem of this location or do you see this behavior >elsewhere?
