I have WR720N TP link router. When I connect straight LAN cable of 1 meter from ISP modem to Routers WAN port, Wifi works perfectly.
When I increase length of the cable to 20 meters, router does not detect the cable
. When I connect same cable to PC, internet work fine.
I simplified the question so that, I could explain it easily.
I now think I shouldn't have done that. Let me explain it fully.
I have two wifi Routers. D-Link DIR-600L and TP Link WR720N. I connect D-Link to Modem. TP link is connected to D link with LAN cable. When I use SHorter length cable everything works fine. SO, no configuration issue, I think.
When I use longer length cable TP link do not detect the cable
. If I connect that long cable to my PC directly it works fine with 2 mbps internet.
What I could conclude from long internet searching, is that ;
It might not detect because of Half or Full duplex configuration of LAN ports in different routers.
Modem LAN >>> D Link WAN >>> D link LAN 1 >>> TP Link WAN >>> wireless
(WAN configuration may not be ideal, but in my defence
, it works with short length)