It would take years, maybe decades. We saw the same thing with drones. It's impossible to overstate how much the supply chain for modern electronics depends on China. Everything in a router, from the chips to the resistors to the antennae to the coating on the PCBs, comes from there.If you wanted to build it all in America, even if you had unlimited funding it would take forever.

There's no router industry here because there's (mostly) no electronics industry, and to make one you'd need to build all the supply chains and subsidiary industries from scratch.