Need to diagnose ethernet cable capped 100mbps

[Kingfish999]

I am trying to repair the Cat5e ethernet cable thats ran through my attic. House flooded durring hurricane but only the ends needed replacement due to corrosion, rest is well above the flood level. But every time test the cable, it caps at 100mbps. Im not sure why, i need help to figuer this out. Its only ran about 40 meters

I crimped both ends of the cable. i used the tester to verify good connection and correct wiring. I have cut and recrimped both ends several times. i used a multimeter to measure ohms (2.8ohms on all pairs going from one wire to its return). What am i missing?

i found a nick in the cable and i cut that 15 foot section out and made it its own cable. even that 15' section still only gets 100mbps through it despite testing good.

Really trying to avoid running new ethernet cable through the attic

I veriefied with my desktop and laptop and both show 100mbps. i used another cable i had and it does show up as 1gbps so its not the network card

 

[Iron Bars]

Clean the contacts and retry.

 

[Janus67]

Are you wiring with A or B standard? Maybe try the other?

Sorry I don't know what could be causing it, I have a cable that had a similar problem but I just replaced it.

 

[freakdiablo]

Clean the contacts and retry.

I doubt there's much grime/corrosion on the contacts after a retermination, though.

Are you wiring with A or B standard? Maybe try the other?

Sorry I don't know what could be causing it, I have a cable that had a similar problem but I just replaced it.

View attachment 370418

Short of getting a cable certifier - think along the lines of a Fluke LinkIQ - replacement would be my next step. Unless the cable is gel filled, you can still have moisture buildup inside.

 

[Railgun]

All you need is a basic tester to validate continuity (something like this). Most likely, you only have two pair doing it's thing. You need all four pair for gigabit. A/B standard doesn't matter provided they're terminated the same on both ends.

I veriefied with my desktop and laptop and both show 100mbps. i used another cable i had and it does show up as 1gbps so its not the network card

That pretty much gives your answer that it's the cable. Now, while I did say a simple tester is good, there could be instances where even a good test is bunk. I've seen it countless times with both copper and fiber.

 

[freakdiablo]

I crimped both ends of the cable. i used the tester to verify good connection and correct wiring. I have cut and recrimped both ends several times. i used a multimeter to measure ohms (2.8ohms on all pairs going from one wire to its return). What am i missing?

All you need is a basic tester to validate continuity (something like this). Most likely, you only have two pair doing it's thing. You need all four pair for gigabit. A/B standard doesn't matter provided they're terminated the same on both ends.

 

[Railgun]

What's "the tester?"

 

[Kingfish999]

opps didnt know there responses to this thread

i followed the B pattern but as said it shyould not matter as i have done both ends the same.

the copper wire looks perfect every time i cut it. nothing had corrosion on it other than the original connector that went under water. even so i cut off the entire section of wire that did go under water (about 15' section) and still limited to 100mbps. i even crimped and tested that 15' section and it still only read 100mbps. so something about this cable is either bad or im having a weird iss thats repeated on every crimp. but checking ohms showed no excess resistance so everything should work fine.

i might sacrifice a known good cable and recrimp it and see if the issue happens.

if i get time i might go ahread and run new cable. but the attic has limited access and is very tight. if im lucky i can just pull it with the old.

in the mean time i got a cheap usb TP-Link adapter that will hold me over. but it does limit my speed to 280mbps when i have 500mbps provider. but its better than 100mbps

the crimp tool kit inclueded a basic tester similar to Railgun posted, the kit i used was this. and it verified all pins had connection and were in proper order.

Amazon.com