Avira Home Guard is described as 'Your home is smart and therefore vulnerable' and is a Network Monitor in the Network & Admin category. There are eight alternatives to Avira Home Guard for a variety of platforms, including Mac, Windows, Linux, Android and iPhone. The best alternative is Nmap, which is both free and Open Source. Other great apps like Avira Home Guard are Fing (Freemium), Zenmap (Free, Open Source), Wireless Network Watcher (Free) and Fingbox (Paid).
Zenmap is the official cross-platform GUI for the Nmap Security Scanner. It is free and runs on Linux, Windows, Mac OS X, etc. Zenmap aims to make Nmap easy for beginners to use while providing advanced features for experienced Nmap users.
Fingbox is a cloud system to monitor and manage your network, based on Fing Apps, Applications and Tools. It's a secure, cross-platform, comprehensive solution to discover devices, scan services, analyze and customize your networks, from anywhere.
Rumble is a network discovery platform that enumerates the network topology, identifies devices, and creates an asset inventory. Rumble runs discovery scans via a locally installed agent or using the standalone Rumble Scanner on the command-line.