I am trying to do a back to back test on a pair of Cambium PTP-820S units. When I bring up the radios (TX Mute OFF) the managment port drops out and shuts down. I have rebooted the radios and switchs, but the port shows no ethernet traffic.
How have you provisioned the Ethernet Services?
For example, if you've connected the MNG Service to the radio port, you may have created a loop.
Check out the in-band and out-of-band management options here: http://community.cambiumnetworks.com/bstrc49894/attachments/bstrc49894/forums_ptp_820/356/1/9.5%20Radio%20Management%20Configuration%20-%202016-09-16.pdf
I hope this helps!