Cambium ePMP 2000 droppes connection if set on 1GIGF/D

Hi There maybe someone can help me here. I don’t have the same issue where the POE dies, however, I have an issue with an ePMP 2000 radio in PTMP mode. it connects to my RB2011 Mikrotik on 1GIG but about every 20min the port disconnect and reconnects causing my PPPOE clients to drop briefly. the only way I can bypass this is by forcing the radio and router port to 100F/D. Any idea what I can do to fix this that the unit stays connected on 1GIG. have even gone and replaced 2011 with a new router and new cable, the problem remains. I have a Cambium PTP650 on the same router but does not goes off and on.
Have changed PSU multiple times but no Luck. Please help!!

these types of issues are hard to pin down without more info:

Are you an an radio tower or near one?
Do you have LPUs installed?
you say you replaced the cable, did you use STP or UTP? is the cable verified with an analyzer ( not a general tester)?

Have you tried a different radio?

My best guess is a poorly terminated or routed cable, but that can change based on what you say above.