NFS has 3 settings in Lion Server: nbDaemons, the number of NFS daemons, useTCP, whether or not TCP is used and useUDP, whether or not udp is used. To disable UDP forces TCP: serveradmin settings nfs:useUDP = 0 Or to turn UDP back on: serveradmin settings nfs:useUDP = 1 To disable TCP if you’d rather just use UDP: serveradmin settings nfs:useTCP = 0 Or to turn TCP back on: serveradmin settings nfs:useTCP = 1