A distributed network is provided with mobile user devices, a virtual \u201cVirtual Private Network\u201d server, and a plurality of physical VPN servers, wherein the virtual VPN server allows all mobile user devices to be configured with a single VPN server address, namely that of the virtual VPN server. The ferroelectric material is made of a perovskite or a layered superlattice material. Axially spaced circular guide plates form end boundaries for the fluid pressure chamber and have radial through-slots that cooperate with arcuate slots in juxtaposed pairs of coaxial guide discs to receive opposite ends of the lift rods and effect synchronous radial movement of the lift rods in response to pressure changes within the fluid pressure chamber. 1 wt-% Al2O3 based on the total weight of the composition, the proportion of Li2O to Al2O3 being from 1:1 to 1.