Last spring we had to update our 7100. We went to the release R10.3.2.E not without problems. I want to emphasize that the update was made by Adtran specialists in Huntsville.
Our problem is that our 7100 stop working and restart by itself! It can take between 24 and 36 hours to restart. See the attached picture.
Usually, the failure occur at the end of week. But now the failure happen in the middle of the day.
We tried to disconnect and reconnect the 7100 without results. Does anyone have any idea where the problem come?
I would upgrade to R10.5.3HA which is an extended maintenance release (10.5.x will continue to get bug fixes).
Look at the release notes for 10.3.3 and 10.5.3HA, there are several bugs fixed that can cause reboots. Look under "fixes" for "reboot".