Do the IP addresses of the sites change that often that you need to determine them dynamically? Most wired IP connections should have fairly stable IP addresses and for mobile connections you’ll only see the providers NAT gateway which should have a decent uptime.
Hmmm, only for certain gateways. It looks to be present in status messages for the Semtech packet forwarder, but is missing for gateways using the ttn-gateway-connector protocol. (The Kickstarter gateways)
It was in the gateway metrics as Bertrik answered. Now I remember
No, almost all ISP’s in the Netherlands give the customers a dynamic IP address but it will remain to the customer for a long time. Even when a router restarts, It will get back the same IP address. Some time it will change as the ISP makes an update in their network.
And it would be easy to lookup the IP address in the info form the gateway.