Zabbix for up/down and performance monitoring/alerting. Can use snmp or their agent to extract info. It can apparently do syslog as well but haven’t figured it out yet so instead I’m using openobserve.

Potentially could pull data from Zabbix and openobserve into grafana for dashboards.

Switch - look at a second hand Cisco 3560e or x. You could even go one of the C3560CG-8PC 8 port switches if you can’t go a full rack mount option.

Router / firewall you could use a second hand mikrotik 750 or 951

Right. That’s different, it originally read as if the port was hanging off the side of your house.

What you need is a managed switch, firewall and vlans. Segregate the NVR and Cameras to a separate network, the port to the camera in the garage on the switch gets configured to the secured VLAN. Even if an unmanaged switch connects it’ll be stuck in that vlan. A good switch will also detect that switch connection and shut it down.

And then only allow specific devices on your “internet” vlan contact the NVR. This will stop anyone connecting to that port and accessing other parts of the network.

Well, what is the risk here exactly?

Are you worried about them accessing your network resources? If so - why are they open slather anyway - you really should be using strong authentication methods on networked equipment.

If you’re worried about them sniffing your network - just how long do you think someone is going to spend sitting outside your house with a laptop to do so?

You could setup some sort of monitoring device so that if the camera goes offline you get notified.

Doesn’t your camera give motion alerts?