Feature request: Option to configure a WAN interface to run the speed test on

[shravyauchil]

Is it possible to add a feature to allow users to run speed test on a specific WAN interface? Currently, the tool tests the default or primary interface, but it would be beneficial to have the ability to configure a specific interface for more targeted performance testing. The request stems from the use case of running speed test on a server setup (node.js) with multiple WAN interfaces.