CAT5E cable auto negotiates 100Mbps, bad cable?

[HeyItsChris]

My CAT5E 25 ft cable auto negotiates to 100Mbps & if I force it to 1Gbps full duplex on both machines (it's a direct connection) it cuts out entirely.

 

I already got a refund on the cable but I'd like to know if it's simply a bad cable?  Is there software out there that can test the pair(s) to see if there is a weak link?

Thanks

[bonami2]

If both machine have the driver and higher than 100mbps ethernet port probably the wire is bad.  I had some old wire that did stuff like that.  Ethernet cable should run a full bandwith without any tweak on windows and linux os.

[ENTERPRISE]

Yeah, likely a bad cable. They can go bad fairly easily if not in a static position, such as fixed to a wall or in conduit. If you have them coiled up and used over and over (I do) then they can go bad, especially CAT5 I find but that is because they are so easy to bend back and fourth which will wear at the copper wires inside. Sheilded/Sheathed cable is far hardware to bend, thus preserves the copper more so.  CAT6 S/FTP cables I love, strong, sheilded but not as flexible, though you can still get a good enough radius to go round the corner of a wall, so it is not like it does not move at all, but can be a little more of a fight lol.

 

As @bonami2 has said, assuming there isn't funky drivers issues (Highly unlikely), then you will be fine with a new cable. 

 

You can get cable testers to ensure correct pairing and connection. Google will easily find one "RJ45 Cable Tester" 

 

But I wouldn't invest in one as its likely just a cable which is easier and quicker to replace. 

 

My other advice is to also have spare cables on hand to test if you think you have a bad cable as you can validate that with a spare very quickly. 

[PCSarge]

this sounds like a bad cable to me, ive had this plenty in office setups before, especially if a cable has been coiled, or in my case, stored on the 1000FT spool in the spool box for a really long time.

 

and before anyone asks.....i pull cat5e/cat6/cat7 (depending on site requests) in large office building as a side job for $$ in college. ive had spooled cable be bad when testing after a pull before, its annoying but very very possible if its coiled or its being stretched to its limit by someone. if you boguht it off a store or from amazon and its defective, return/refund it and toss it. and one thing ive learned from customers cheaping out MONOPRICE cables tend to be pretty low quality of materials and have the most issues.

Edited June 6, 2022 by PCSarge