I manage 5 different schools. At one school we had similar problems with AFP disconnects 😕 One of the problems we found was some of the switches and or routers had the spanning tree protocol enabled. According to Cisco’s website “Spanning-Tree Protocol is a link management protocol that provides path redundancy while preventing undesirable loops in the network. For an Ethernet network to function properly, only one active path can exist between two stations. ” As soon as we disabled this protocol almost all disconnects stopped. I hope this helps someone. I was pulling my hair out, checking server settings, and the whole time I had nothing to do with it.