I've found some major basebuilding issues with Fences and probably also with Watchtowers.
If you destroy a wall from the outside and destroy the Frame too, the collision box stays the same and you cannot crouch under the Fence. A restart will fix the issue, but there is a even bigger Problem with that !
If you start to build the part destroyed again and the dismantle it from the inside, the server will crash with Exception code: C0000005 ACCESS_VIOLATION at 7C496050 !
I tested it on my Modded Server and also on a completly Vanilla Server. It's not a Mod issue !