You can use the getNetworkDeviceUplink API to fetch the IP address, gateway, public IP address etc, but as @PhilipDAth mentioned, the API cannot currently provide the link speed and LLDP information of the connected switch (for example). Here's an example for my home MR56:
I'd recommend using the "Make a Wish" button to submit this as a requested new feature.
Thanks, all @PhilipDAth, @ConnorL, and @Edgar-VO. I have checked using getNetworkDeviceUplink API to get IP address, gateway, public IP address etc. And I also want to get Ethernet information but well, I am going to suggest it to 'Make a Wish.'