When you update your eero network to the latest version of eeroOS, only the active eeros on your network will update. If one or more of your eeros are offline (such as being unplugged or no longer in use), the offline eeros will not be updated until they are powered back on and connected to the network. Once connected, the eero app will prompt you to update the new eero to same eeroOS version as the rest of your network.