What's wrong with my custom LAN cable?

The twisted pairs matter.

The conductors connected to the following pin pairs must be twisted together:
1 & 2
3 & 6 <-- Note: NOT 3 & 4.
4 & 5 <-- Note: NOT 5 & 6.
7 & 8

A simple cable tester like that can't tell which pin pairs are on the same twisted pair within the cable. It can only tell if you've got the right pins connected to the right pins.

Each pair is a balanced transmission line that uses differential signaling to cancel out noise. If you get the pairs wrong, you lose a lot of the ability to reject noise, which can make the link unusable.

I have been crimping cables for well over 12 years, all kinds of cables (mostly cat5e) with standard connectors with the 568B configuration, pass trough and letting the switches take care of the cross over

i have been using a tester all this years, but also take the precaution of testing the cables with a laptop or pc as well when possible

Last night i brought home a cable i made which passed the tester ok, but for the life of me would not work on any of my home computers at all, light would not come on and pc's would not even recognize the cable being inserted

I ended up rewiring the ends 3 times each and it still didnt work, yet the tester said it was ok

I finally made it a cross over (swtiching green with oranges) and it worked. im still stumped since all my other currently working cables are 568B pass trough.

My only answer is that this cable is somehow damaged and crossing over strengthened the signal?

So far connection is good at either 100 and 1000 mbps.

Wanted to share this weird case.

I have the same tester!

I would recommend you look at both sides of the tester and make sure every light flashes in the correct order as it possible that there could be a wrong order at one end of the cable.

If however both all light up in order, I am out of ideas - sorry!

The instructions you listed that you followed give the wrong wire order for a patch (router-to-PC) cable. The order on that cable appears to be for a crossover (PC-to-PC) cable (but I have not made one of those in a while). The correct order is, left to right with the clip side down:

• Orange-white stripe
• Orange
• Green-white stripe
• Blue
• Blue-white stripe
• Green
• Brown-white stripe
• Brown

Try re-crimping both ends of the cable in that pattern.

Obviously something is not ok. Did you nick any of the wires? are you sure you can see the copper touching the end of the plug? Are the lights on the tester flashing in the right order? Have you verified your tester is working correctly on a good and obviously not good cable? Try crimping each end multiple times, sometimes that helps if you bought a cheap crimper (it should be a full cycle ratchet for a decent connection).

Also of concern, if you are running it through a wall, why are you not punching it down into a jack and putting it into a faceplate? Its a much more secure and stable connection for that sort of thing.