LAN cable: 20 meter or 10 meter long can not work

First

i use lane wire 20 distance from Type2 modem to laptop. can nor work , continuty is ok.

second

Type 2 modem is in center.

Desktop is 10 m left.

Laptop is 10 m Right.

Result

4 pair wire continuty is both side ok.check by multimeter.

sometime lane connect OK then after tangle mark then after disconnect.

what may i do give advice.