Could an internet router made by a Chinese company — and used in millions of American homes — harm U.S. national security? Three U.S. federal agencies are examining whether products sold by TP-Link could be used to facilitate cyberattacks. The probes could result in a ban that would upend the U.S. consumer router market, in which TP-Link is a top-two player. The investigations into TP-Link follow years of increasing scrutiny of Chinese telecommunications firms, as hacking threats linked t