connection appeared plugged / unplugged

Hello,
Please I want your help to solve my problem.
We made a home network (8 pcs) without server to using DSL line with rotor (4 ports) and switch (8port),
The largest cable (utb) length was 70 m.
And I made the arrange of the coolers wires on the cable like t568b 1-whait/oringe 2-oringe
3-white/green 4-blue
5-white/blue 6- green
7-white/brown 8- brown
Now the network is established but it is so slowly and the net line is good
But the problem for me my network is appeared pluged/unplged in my pc my cable length is 55m only my pc.
I think the cable is cutted but I checked it was good, may be it passing near electrical cable I do not now ??????????????????? ther is limitted distance between utb cable and electrical cables????????????????
Please help me