Upgrade PTP600 from 8.1 to 8.5, 9.1

Hi we have 2 link ptp600lite without problems with:
hardware version: D04-R02-C
software version: 8.1

I tried to upgrade to 8.3 and 8.3 but they presents issues like: no ping response, resets but the service end-to-end is up. Then we have to return all radios to version 8.1
We compared with other link which comes here with hardware D05-R02-C-FPS and version 8.3 and works good. The question is do you know if something wrong happen with those hardware version??