Slow Ethernet jack

[dismas]

One Ethernet jack in my house is slower than the others. Iperf measures 1 Gbit/s between PCs on all other jacks, but only 95 Mbit/s to the slow jack. A network cable tester finds no issues with the cable going to the slow jack. However, all cables in the wall are Cat 5 (not 5e). Am I just getting lucky with all the other Ethernet jacks? Or is there possibly some other issue affecting this jack's speed?

 

[L&LD]

You're just getting lucky with the others.

Is this problem jack the furthest run?

 

[bbunge]

One Ethernet jack in my house is slower than the others. Iperf measures 1 Gbit/s between PCs on all other jacks, but only 95 Mbit/s to the slow jack. A network cable tester finds no issues with the cable going to the slow jack. However, all cables in the wall are Cat 5 (not 5e). Am I just getting lucky with all the other Ethernet jacks? Or is there possibly some other issue affecting this jack's speed?

More likely the jack or patch cable used for testing is not connecting all 4 pair of wires in that one cable. Your 100 MB (nominal) tells me that just two pair of wires are connected. Or the cable is not punched down correctly. If you are using just a continuity tester it may not show if the jack is connected per TIA/EIA 568A or B. And CAT 5 is still good enough for a GB connection. Granted, 5e is better.

 

[dismas]

You're just getting lucky with the others.

Is this problem jack the furthest run?

No, it's about half as long as the longest run.

More likely the jack or patch cable used for testing is not connecting all 4 pair of wires in that one cable. Your 100 MB (nominal) tells me that just two pair of wires are connected. Or the cable is not punched down correctly. If you are using just a continuity tester it may not show if the jack is connected per TIA/EIA 568A or B. And CAT 5 is still good enough for a GB connection. Granted, 5e is better.

I'm using a cable tester that blinks 1 through 8, one at at time (tested by connecting the main body to the Cat 5 cable and the remote to a Cat 5e cable plugged into the Ethernet jack). It gives normal results, doesn't that mean that all the wires are connected correctly per TIA/EIA 568A or B?

 

[thiggins]

No, it's about half as long as the longest run.


I'm using a cable tester that blinks 1 through 8, one at at time (tested by connecting the main body to the Cat 5 cable and the remote to a Cat 5e cable plugged into the Ethernet jack). It gives normal results, doesn't that mean that all the wires are connected correctly per TIA/EIA 568A or B?

No. It just means that each wire is connected to the same pin on both ends. The wires could be from different twisted pairs in the cable.

@bbunge has the correct hint. 95 Mbps indicates only two pairs are working. You need 4 for Gigabit. Best things is to pull the sockets out of the wall and compare the connections on both ends with known good jacks.

 

[dismas]

No. It just means that each wire is connected to the same pin on both ends. The wires could be from different twisted pairs in the cable.

Can you elaborate on this? The free end of the Cat 5 cable is T568B, so if the network cable tester shows correct output, doesn't that mean that the white/orange wire is connecting pin 1 to pin 1, the solid orange wire is connecting pin 2 to pin 2, etc?

 

[thiggins]

The cable tester doesn't know what color the wires are. It's just looking for continuity. Someone could have just connected the same color wires to the same pins on both jacks, not following any color code. Twisted pairs must be connected to the correct pins for the standard you are following.
Since you are only getting 100 Mbps and your cable tester is showing connection for all 8 pins, something else is messed up.

 

[dismas]

The cable tester doesn't know what color the wires are. It's just looking for continuity. Someone could have just connected the same color wires to the same pins on both jacks, not following any color code. Twisted pairs must be connected to the correct pins for the standard you are following.

Just to clarify, there's a Cat 5 cable with an RJ45 on one end and the other end is the wall jack (with a Cat 5e cable plugged in). The cable tester shows pin 1 on the Cat 5's RJ45 is connected to pin 1 on the Cat 5e's RJ45, pin 2 is connected to pin 2, etc. If all RJ45s are properly following T568B (confirmed through visual inspection), doesn't that mean orange/white is connecting Cat 5's pin 1 to wall jack pin 1, orange is connecting pin 2 to 2, etc? Wouldn't it show an incorrect sequence like this if the wall jack was wired incorrectly?

Diagram:
[Cable tester master]<----------Cat 5 cable----------wall jack><-------Cat 5e cable--------->[Cable tester remote]

 

[Tech9]

I would have fixed the issue by now by redoing the ends. It's obvious the connection stuck to Fast Ethernet only.

 

[bbunge]

Just to clarify, there's a Cat 5 cable with an RJ45 on one end and the other end is the wall jack (with a Cat 5e cable plugged in). The cable tester shows pin 1 on the Cat 5's RJ45 is connected to pin 1 on the Cat 5e's RJ45, pin 2 is connected to pin 2, etc. If all RJ45s are properly following T568B (confirmed through visual inspection), doesn't that mean orange/white is connecting Cat 5's pin 1 to wall jack pin 1, orange is connecting pin 2 to 2, etc? Wouldn't it show an incorrect sequence like this if the wall jack was wired incorrectly?

Diagram:
[Cable tester master]<----------Cat 5 cable----------wall jack><-------Cat 5e cable--------->[Cable tester remote]

Also possible that a Jack is not making connection to all the pins in the lan card