Wired internet connection via router slower than direct

Question

I am using cable internet.
When I am connecting LAN cable directly to PC download speed is 20 Mbps (this is my Internet connection speed according to the agreement with provider) When I am using router (Internet cable connected to the WAN port of the router, and PC connected to the one of four LAN ports) download speed is 15 Mbps I tried to turn off Wi-Fi from the router settings to eliminate impact of other wireless devices on tests. No other wired devices connected to the router except the PC. Result always the same on various speed tests - 20 Mbps direct and 15 Mbps through the router.

Can you please hem me out? Why can I get maximum speed with the router?

Router model is Planet WNRT-617 150Mbps 802.11n Wireless Broadband Router http://www.planet.com.tw/en/product/product_ov.php?id=34631

Answer 1

I believe there is always a loss of speed from using a router, but I think your case is significant because that router is optimized for providing the best "wireless" speed to your devices. You can tell that by the fact that this router does not even have 1Gbit connection for wired devices (only 100mbit max), while most modern non-wireless routers would have this "faster" connection standard. I can bet that a non-wireless router will give you better performance.

Cheers. Leo