sensors-software | sourcecode for reading sensor data

Your "repeater" does not extend the existing network as most WiFi repeaters do but is instead a WiFi router which creates a new network with a different address space. Your main WiFi router ("main SSID") is then just a single device inside this new network, which means it will use NAT to provide access from any devices inside "main SSID" to the "repeater SSID".

But since this kind of NAT dynamically maps multiple IP to a single IP it can work by design only in one direction: connection from inside the "main network" (192.168.1/24) to the "repeater network" (10.24.1/24) can be created but no connection from the repeater network to the main network. That's actually the same reason why devices inside a home network are not directly reachable from the internet.

To make this work you would need to create an explicit port forwarding if your router for "main SSID" can do this. Alternatively you could use a repeater which does not create a new network but which just extends the existing network. No idea if your existing device can do this since it is explicitly documented as "a WiFi NAT router".