Tplink slows down internet

Question

When I introduce a TL-WR841N Router between my PC and Cable modem, the internet speed drops by 50%.

Cable Modem* ----- PC 200 Mbps (via speedtest.net)

Cable Modem* ----Tplink- PC 96 Mbps (via speedtest.net) The Tplink -PC cable is less than 10'

• ARRIS Surfboard SB 6141

Cable internet is Comcast Xfinity.

Answer 1

As I was writing I think I found the solution. Posting for posterity.

The TPLINK specs: 300 Mbps wifi, but, oddly, slower on wired. It's 100Mbps on the WAN/LAN ports.