Question Long Ethernet cable giving slower speed than a short one

Apr 12, 2018
55
0
30
0
Recently I got my internet speed to 250 Mbps, I have installed a new modem "Netgear Orbi" because the old modem wasn't giving 250 Mbps It was only the Fibre.
I've connected the Orbi modem to the Old Fibre "EchoLife HG8247" and I set up the new modem as a router and the problem is that when I use a short wire on the modem it works fine and gives me 250 Mbps and when I use a long wire ~30m it gives only ~100Mbps
Here's a photo from the modem website View: https://imgur.com/a/KBoEYqO

LAN 1 is my PC
LAN 3 is another computer in the house but with a short wire.
I tried also changing the modem to Access point mode and it didn't work.
When I go to the QoS section in the modem website it gives me a Speedtest and it gives me 250 Mbps.
I have tried 3 long wires that is ~30m long, It didn't work and I've bought a new wire and I have tested it in the modem it gave me ~100Mbps and when I tried it in the fibre it gave me 250Mbps.
Edit: When the modem is on router mode the DHCP mode is turned on.
 
Last edited:
The speed of an Ethernet link is negotiated. If your hardware has any defects the adapters will negotiate a slower speed to minimize communication errors. 100 Mbps is one of the standard speeds that could be selected. Normally, people would suggest that you cable has a defect, but since you have tried 3 and it seems the issue only happens when the cable is plugged into the modem, then I suspect that is a very minor flaw in the modem port or electronics. I assume you have tried other ports on the modem. I assume the cables you have tested with are of decent quality.

Potential fix ... use a short cable to a gigabit switch and then use a long cable from the switch to your PC.
 
Apr 12, 2018
55
0
30
0
The speed of an Ethernet link is negotiated. If your hardware has any defects the adapters will negotiate a slower speed to minimize communication errors. 100 Mbps is one of the standard speeds that could be selected. Normally, people would suggest that you cable has a defect, but since you have tried 3 and it seems the issue only happens when the cable is plugged into the modem, then I suspect that is a very minor flaw in the modem port or electronics. I assume you have tried other ports on the modem. I assume the cables you have tested with are of decent quality.

Potential fix ... use a short cable to a gigabit switch and then use a long cable from the switch to your PC.
Are you sure that the gigabit switch solution will work? because I don't think that they sell one of these with a good price in my country so I might have to buy it from the internet.
 
Check the cables you purchased to see they are valid cables. Most cables will have marking printed on them . You want to see if the wire is copper is size 22-24. If the cable say it is CCA or the cable is that thin or flat cable you can have major issues with longer cables.
 
I would had feel more confident on your tests if u had said, tried 5 other cables of DIFFERENT BRANDS AND MAKES 'cuz for all I know they are of the same bad batch.

Anywhoo not a big issue, u just have to weed out whatever bad/outdate stuff u got in there.
 
Apr 12, 2018
55
0
30
0
I would had feel more confident on your tests if u had said, tried 5 other cables of DIFFERENT BRANDS AND MAKES 'cuz for all I know they are of the same bad batch.

Anywhoo not a big issue, u just have to weed out whatever bad/outdate stuff u got in there.
But I bought another 30m Ethernet cable and it didn't work so I've returned it to the store, The problem is that if I connect any of the 30m cables that I have in the Fibre it works fine but if I connect them to the new modem they work at 100Mbps speed, Only short cables work with the new modem at 250 Mbps.
 
The main issue is there is a lot of fake cable being sold now days. I would bet the vast majority of cables you find on amazon are CCA cables, you have to actually put in solid copper to get hits. At least amazon now requires them to reveal that the cable is not copper. It is extremely common for substandard cable to run on one piece of equipment and not others it all depends on the tolerances in the chips

There are not a lot of possibilities it is a bad cable or a bad port. Bad cables are much more common and you have few option if the port if defective so you hope it is the cable.
 
Apr 12, 2018
55
0
30
0
The main issue is there is a lot of fake cable being sold now days. I would bet the vast majority of cables you find on amazon are CCA cables, you have to actually put in solid copper to get hits. At least amazon now requires them to reveal that the cable is not copper. It is extremely common for substandard cable to run on one piece of equipment and not others it all depends on the tolerances in the chips

There are not a lot of possibilities it is a bad cable or a bad port. Bad cables are much more common and you have few option if the port if defective so you hope it is the cable.
What makes the 30m work only in the fibre but not in the new modem?

And what do you think about the gigabit switch solution that @anotherdrew suggested, Would it work?
https://www.amazon.com/TP-Link-Ethernet-Optimization-Unmanaged-TL-SG105/dp/B00A128S24
 
You would have to connect the cable to a very special meter used to certify cable to tell what is actually wrong with it. Most these meters cost close to $1000 and are used by professional cable installers. Some patch cable vendors will test and printout results for every cable they sell but this adds to the costs. For us average people there is no way to know why a cable does not function.

That switch is one of the most popular inexpensive switch being sold. I have a couple of them even though they are in a box since I needed PoE switches.
 
Apr 12, 2018
55
0
30
0
You would have to connect the cable to a very special meter used to certify cable to tell what is actually wrong with it. Most these meters cost close to $1000 and are used by professional cable installers. Some patch cable vendors will test and printout results for every cable they sell but this adds to the costs. For us average people there is no way to know why a cable does not function.

That switch is one of the most popular inexpensive switch being sold. I have a couple of them even though they are in a box since I needed PoE switches.
So should I bring a network technician?
 
You can buy lots of cable and even a new router for what it will cost to hire someone.

Just very carefully check you cables. They should be marked with the type of wire and the size of the wire. They generally say EIA/TIA on the side which is the certification standard. I have only heard of 1 vendor from china that actually put EIA/TIA on fake cables.
 
Apr 12, 2018
55
0
30
0
You can buy lots of cable and even a new router for what it will cost to hire someone.

Just very carefully check you cables. They should be marked with the type of wire and the size of the wire. They generally say EIA/TIA on the side which is the certification standard. I have only heard of 1 vendor from china that actually put EIA/TIA on fake cables.
The cable I'm using right now says "TYPE 24AWG/4PAIRS UTP VERIFIED CM CAT.6 PATCH CABLE TO TIA/EIA 568A CSA TYPE CMGFT4265M MADE IN CHINA"
Anyways, Why does this cable work on the fibre but not the modem??
 
You are back to it being a bad port if the cable is actually good. Again I can't tell you what if anything is wrong with the cable without a meter to test it. These meters test all kinds of technical details like how much cross talk on certain frequencies. It all doesn't matter the only option with a cable are replacing the ends if there is something wrong with the way the wires are twisted inside the cable you can't fix that anyway.
 
Personally I wouldn't trust any cable markings, specially from China. Chinese lumbers marked as blah-blah certified blah-blah, because they are obligated to do so by law, turn out to contain chemicals several times higher than mandated, not to scare you.
 
As Bill was saying, professionals have tools to test their hardware and pinpoint issues. As home users we have to make do with what we have.

In your situation ... you have 3 cables that all allow for a gigabit connection when connected from device 1 (fibre modem) to PC. We can say with 95% certainty that all the hardware is working properly. Now, when you connect from device 2 (Orbi router) to PC using the same 3 cables you can not get a gigabit connection. We can be 90%+ certain that issue is with what has changed in the scenario (device1 changed to device 2). The normal fix would be to replace the malfunctioning device (Orbit router). We never really discussed if that was a possibility.
 
Apr 12, 2018
55
0
30
0
As Bill was saying, professionals have tools to test their hardware and pinpoint issues. As home users we have to make do with what we have.

In your situation ... you have 3 cables that all allow for a gigabit connection when connected from device 1 (fibre modem) to PC. We can say with 95% certainty that all the hardware is working properly. Now, when you connect from device 2 (Orbi router) to PC using the same 3 cables you can not get a gigabit connection. We can be 90%+ certain that issue is with what has changed in the scenario (device1 changed to device 2). The normal fix would be to replace the malfunctioning device (Orbit router). We never really discussed if that was a possibility.
I'll go for the gigabit switch solution. I tried connecting the Orbi router to another electric plug it didn't work and I have also tried putting the long wire to the Orbi satellite.
 

ASK THE COMMUNITY

TRENDING THREADS