Ethernet trouble with PTP-550

I have a PTP 550 that feeds to a Cisco switch and then feeds three Force 200 radios carrying data to three other broadcast towers. My problem is that the 550 seems to be having trouble with the Ethernet end. It will not negotiate to 1 Gig and sometimes will show 100 M and often ends up at 10 M. I checked the cable and connectors and all is normal. There is quite a bit of RF on this tower and the cable runs past a couple of FM antennas on it’s way to the ground. The Force 200 radios don’t seem to be having this problem. Could this be a problem with the RF getting into the Ethernet cable? It is shielded. I am going to check the grounds on the shield next. Anybody else seen something like this with the 550? I’m afraid that if I turn off the auto negotiate that I might loose contact with the radio altogether.