Recommended and mentioned products
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pfSense is a free and open source firewall and router that also features unified threat management, load balancing, multi WAN, and more
Https://pfsense.org (netgate hardware is used in businesses).
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OPNsense® you next open source firewall. Free Download. High-end Security Made Easy™. Offers Intrusion Prevention, Captive Portal, Traffic Shaping and more.
Https://opnsense.org/ just like pfsense but for some reason branched development.