I recently purchased a 4G/LTE USB modem to use on a laptop. It uses the MS generic RNDIS driver. I can also attach my cell phone (in "tether" mode) to the laptop. That also uses the RNDIS driver.

When I connect the USB modem something - and I assume that "something" must be the driver - invokes my default browser (Firefox) and automatically connects to modem's admin/management HTTP server. When I connect the cell phone the browser is not invoked.

I don't understand the invocation of the browser. I double checked to make sure it's not an Autoplay/Autorun setting invoking the browser but I have them disabled. (And I don't think Autorun could have set the IP addr anyway.)

Would the driver really be built to invoke a browser?
The only alternative I can think of is that data from the connection (which looks like Ethernet over USB, I think) could automatically invoke my default browser. I hope that's not possible.

BTW, the operating system is Win 10 20H2, but I don't think that matters much.