Compact fanless firewall appliance offers 6x 2.5GbE ports for $230 and up - CNX Software
Amazon.com: KingnovyPC Firewall Micro Appliance, 6 Port i225 2.5G LAN Fanless Mini PC Celeron J4125, No Ram No SSD Gigabit Ethernet AES-NI VPN Router Openwrt Barebone : Electronics
CISCO ASA5515-K9 Security Appliance | Netmode
Amazon.com: Protectli Vault Pro VP4630-6 Port, Firewall Micro Appliance/Mini PC - Intel i3, 2.5G Ports, DDR4 RAM, M.2 NVMe or SATA SSD Storage, AES-NI, 8GB RAM, 120GB SATA SSD : Electronics
Juniper Networks SRX300 6-Port Security Services Gateway Firewall - No Power Sup | eBay
R6264S WatchGuard Firebox x500 Firewall Firewall 6-Port 5 ConnEtcions EN Fast EN 1U
Protectli Vault FW6A - 6 Port Intel® Celeron - Protectli US Store