Cat 6 cable

[S6PNJ]

I'm having a few issues with a broadband connection and one of the fault finding methods that my ISP has asked me to try is to use a CAT 6 cable between the router and my PC/laptop. Now,firstly, I'm as sure as I can be that the low broadband speeds are not an issue of my network or kit, as I've connected via 802.11ac (5Ghz) network within 1-2m of the router with no other equipment connected or switched on and still don't get the claimed speeds. I've connected my laptop (2017 Core i7 with 8Gb RAM and 256GB SSD, so no slouch!) via a few Ethernet cables I already have stashed around the place, and get ridiculously low speeds of 40-50 Mbps as opposed to the 250-300Mbps I get via 5Ghz WiFi. The connection in question connection is 900Gbps up and down for reference, FTTP (Gigaclear). Sadly it's not my home connection but one in a business premises.

I therefore bought a 'claimed' CAT 6 cable from a well known auction site and it has arrived - it's a flat cable type which immediately raised my suspicions. Now, it states CAT 6 on the cable, but anyone can have that printed on without it actually being CAT 6. It doesn't get me any faster speeds between my router and laptop but I'd like to be able to check it out if possible as a CAT 6 against a CAT0 5 or 5e cable if I can.

Other kit I possess that could be used is a Synology 2 bay NAS, various old ISP routers, the 2 routers I currently use on another network (Asus N55U and a TP-Link 450M, another laptop (Samsung NP350V5C - i3 with 6Gb RAM), a desktop (homebrew but with an i3 and 8Gb RAM running of a MSI Z77A G43 motherboard that supports 10/100/1000 networking.

So is there any relatively simple test I can do with the above kit to check if the (cheap and nasty) cable I've bought is actually a CAT 6 and not just a plain old CAT 5/CAT5e cable?

Oh and in case anyone asks, it has been escalated through the ISP's procedure and I'm waiting for them to take action, so I've already raised the connection speeds with them - this testing of the CAT 6 cable is for my knowledge and piece of mind (and also to claim back from the seller if he's sold me a phoney cable - which I suspect).

[Mr Pointy]

The Cat6 cable is a red herring; a Cat5e will easily support Gigabit speeds. You'll struggle to make any meaningful tests on the cable without a proper cable verifier though.

[bristolracer]

S6PNJ said:

So is there any relatively simple test I can do with the above kit to check if the (cheap and nasty) cable I've bought is actually a CAT 6 and not just a plain old CAT 5/CAT5e cable?

No

Unless you can get your hands on a Fluke cable tester (about £7500 last time i looked) and even then im not sure it would see much difference over such a short cable.

Try your laptop on another broadband connection/ router try another laptop, always test the test equipment.

[TonyRPH]

Does the output of netstat -s show any errors?

If you see a lot if interface errors that would be a starting point to diagnosing any issues.

[S6PNJ]

Mr Pointy said:

The Cat6 cable is a red herring; a Cat5e will easily support Gigabit speeds. You'll struggle to make any meaningful tests on the cable without a proper cable verifier though.

Also what I'd read for over short distances.

bristolracer said:

Unless you can get your hands on a Fluke cable tester (about £7500 last time i looked) and even then im not sure it would see much difference over such a short cable.

One internet thread I'd read, said that even with a tester 80% of Cat 6 cables failed the Cat 6 test!

bristolracer said:

Try your laptop on another broadband connection/ router try another laptop, always test the test equipment.

Thanks - good shout! I've tried 3 laptops on this connection, all 'reasonably' modern, none of which give different speeds, but I've not tried my equipment on another connection - more tricky! Though if I can persuade my neighbour to let me try, he has a 300Mbps FTTP connection.

Edited by S6PNJ on Wednesday 6th November 12:21

[cashmax]

The cable is unlikely to be the problem, as has been said, cat 5 will give a reliable gig connection over short distances, but since you have 2 laptops, why not just connect them through either a switch or directly and run iperf or simalar, which will at least check that the hardware you are using will support decent throughput.

Edited once I re-read your post to say it sounds more like a port duplex mismatch on a switch router is causing your low speed issues when hardwired.

Edited by cashmax on Wednesday 6th November 12:50

Edited again to say you should test speed with cable just between laptops and then through the same hardware that hosts the WAN connection. When you tested with the new cables are you connecting directly into the Gigaclear router or is there other hardware involved?

Edited by cashmax on Wednesday 6th November 12:53

[S6PNJ]

cashmax said:

The cable is unlikely to be the problem, as has been said, cat 5 will give a reliable gig connection over short distances, but since you have 2 laptops, why not just connect them through either a switch or directly and run iperf or similar, which will at least check that the hardware you are using will support decent throughput.

Edited once I re-read your post to say it sounds more like a port duplex mismatch on a switch router is causing your low speed issues when hardwired.

Agreed, I'm as sure as I can be that the cable/wifi is not the issue, it is the router/connection that is giving me low speeds, but I'd like to check my 'kit' where possible.

The router is as per supplied, no 'tinkering' has gone on from my point of view but it is a Genexis DRG739v2. How would I check for a port duplex mismatch?

I can give iperf a go (once I've read up on it and know what to do!

[TonyRPH]

S6PNJ said:

cashmax said:

The cable is unlikely to be the problem, as has been said, cat 5 will give a reliable gig connection over short distances, but since you have 2 laptops, why not just connect them through either a switch or directly and run iperf or similar, which will at least check that the hardware you are using will support decent throughput.

Edited once I re-read your post to say it sounds more like a port duplex mismatch on a switch router is causing your low speed issues when hardwired.

Agreed, I'm as sure as I can be that the cable/wifi is not the issue, it is the router/connection that is giving me low speeds, but I'd like to check my 'kit' where possible.

The router is as per supplied, no 'tinkering' has gone on from my point of view but it is a Genexis DRG739v2. How would I check for a port duplex mismatch?

I can give iperf a go (once I've read up on it and know what to do!

This is why I offered the following suggestion - but the OP seems to have missed it,,,

TonyRPH said:

Does the output of netstat -s show any errors?

If you see a lot if interface errors that would be a starting point to diagnosing any issues.

[cashmax]

TonyRPH said:

S6PNJ said:

cashmax said:

The cable is unlikely to be the problem, as has been said, cat 5 will give a reliable gig connection over short distances, but since you have 2 laptops, why not just connect them through either a switch or directly and run iperf or similar, which will at least check that the hardware you are using will support decent throughput.

Edited once I re-read your post to say it sounds more like a port duplex mismatch on a switch router is causing your low speed issues when hardwired.

Agreed, I'm as sure as I can be that the cable/wifi is not the issue, it is the router/connection that is giving me low speeds, but I'd like to check my 'kit' where possible.

The router is as per supplied, no 'tinkering' has gone on from my point of view but it is a Genexis DRG739v2. How would I check for a port duplex mismatch?

I can give iperf a go (once I've read up on it and know what to do!

This is why I offered the following suggestion - but the OP seems to have missed it,,,

TonyRPH said:

Does the output of netstat -s show any errors?

If you see a lot if interface errors that would be a starting point to diagnosing any issues.

I have a feeling that netstat might show too much info for the OP to interpret.

[cashmax]

S6PNJ said:

cashmax said:

The cable is unlikely to be the problem, as has been said, cat 5 will give a reliable gig connection over short distances, but since you have 2 laptops, why not just connect them through either a switch or directly and run iperf or similar, which will at least check that the hardware you are using will support decent throughput.

Edited once I re-read your post to say it sounds more like a port duplex mismatch on a switch router is causing your low speed issues when hardwired.

Agreed, I'm as sure as I can be that the cable/wifi is not the issue, it is the router/connection that is giving me low speeds, but I'd like to check my 'kit' where possible.

The router is as per supplied, no 'tinkering' has gone on from my point of view but it is a Genexis DRG739v2. How would I check for a port duplex mismatch?

I can give iperf a go (once I've read up on it and know what to do!

You have already said that the WAN (internet) connection will do north of 200Mbps with wifi, which tell us that the internet connection is NOT the issue. The problem you have is on your side of the router.

That router is reliable, but not great for info. You need to tell us if there is anything between the router and your laptop in the test you are doing.

The only way to tell what speed the ports have negotiated at on that router is by looking at the leds on the lan ports. Green means 1000Mbps, yellow means 10/100mbps. So if you are connected directly to a lan port on the router you can either check your laptop to see what speed it says you are connected at or check the router and see what colour the led on that port is.

If you are not connecting direct to the router, then trace exactly which way you get to it (via a switch for example) and then check which lan port that switch is connected to on the router and what colour the led is.

In fact just check the router and see if there are any connected lan ports with a yellow light, because they will not be able to exceed 100mbps best case.

Perhaps your laptops only have 100mbps lan ports or the speed is hard coded to 100mbps for some reason or more likely.

[S6PNJ]

cashmax said:

TonyRPH said:

S6PNJ said:

cashmax said:

The cable is unlikely to be the problem, as has been said, cat 5 will give a reliable gig connection over short distances, but since you have 2 laptops, why not just connect them through either a switch or directly and run iperf or similar, which will at least check that the hardware you are using will support decent throughput.

Edited once I re-read your post to say it sounds more like a port duplex mismatch on a switch router is causing your low speed issues when hardwired.

Agreed, I'm as sure as I can be that the cable/wifi is not the issue, it is the router/connection that is giving me low speeds, but I'd like to check my 'kit' where possible.

The router is as per supplied, no 'tinkering' has gone on from my point of view but it is a Genexis DRG739v2. How would I check for a port duplex mismatch?

I can give iperf a go (once I've read up on it and know what to do!

This is why I offered the following suggestion - but the OP seems to have missed it,,,

TonyRPH said:

Does the output of netstat -s show any errors?

If you see a lot if interface errors that would be a starting point to diagnosing any issues.

I have a feeling that netstat might show too much info for the OP to interpret.

Tony, I missed your comment earlier - I was doing a quick reply over lunch - and cashmax, no I can understand the output fine thanks (I think). The connection is in my local village hall and I've not had the opportunity to do any further testing - maybe tomorrow... but on my home network, netstat -s shows me 24 received address errors out of 618099 packets received (IPv4), 0 under IPv6 (only 309 packets received), no errors under ICMPv4, 5 receive errors for UPD for IPv4. But this is all by the by as its a simple cable I want to test, not the internet link via FTTP/Gigaclear.

cashmax said:

You have already said that the WAN (internet) connection will do north of 200Mbps with wifi, which tell us that the internet connection is NOT the issue. The problem you have is on your side of the router.

Cashmax, time for a step backwards I think - I'm not trying to trouble shoot the lower speeds via Ethernet, I'm not trying to solve issues with the connection - that's up to Gigaclear to sort (it should be a 900Mbps up/down FTTP connection), I'm trying to find out if there is a way I can test/prove or otherwise see if the cable I bought is Cat 6 or not.

Ref the speed I am seeing, any physical connections I've made to the router, they are all direct, no other gear being used simply router-ethernet cable-laptop. WiFi is on the 5Ghz signal, no other devices connected via ethernet or WiFi, connecting via 802.11ac (but again, Gigaclear are troubleshooting the speeds/connectivity - in theory......)


And if you want the full netstat -s from my home connection via WiFi it's here:


IPv4 Statistics

Packets Received = 618099
Received Header Errors = 0
Received Address Errors = 24
Datagrams Forwarded = 0
Unknown Protocols Received = 0
Received Packets Discarded = 5783
Received Packets Delivered = 619431
Output Requests = 471293
Routing Discards = 0
Discarded Output Packets = 10
Output Packet No Route = 75
Reassembly Required = 0
Reassembly Successful = 0
Reassembly Failures = 0
Datagrams Successfully Fragmented = 0
Datagrams Failing Fragmentation = 0
Fragments Created = 0

IPv6 Statistics

Packets Received = 309
Received Header Errors = 0
Received Address Errors = 0
Datagrams Forwarded = 0
Unknown Protocols Received = 0
Received Packets Discarded = 1456
Received Packets Delivered = 2063
Output Requests = 3740
Routing Discards = 0
Discarded Output Packets = 0
Output Packet No Route = 0
Reassembly Required = 0
Reassembly Successful = 0
Reassembly Failures = 0
Datagrams Successfully Fragmented = 0
Datagrams Failing Fragmentation = 0
Fragments Created = 0

ICMPv4 Statistics

Received Sent
Messages 1093 1261
Errors 0 0
Destination Unreachable 1093 1261
Time Exceeded 0 0
Parameter Problems 0 0
Source Quenches 0 0
Redirects 0 0
Echo Replies 0 0
Echos 0 0
Timestamps 0 0
Timestamp Replies 0 0
Address Masks 0 0
Address Mask Replies 0 0
Router Solicitations 0 0
Router Advertisements 0 0

ICMPv6 Statistics

Received Sent
Messages 4 45
Errors 0 0
Destination Unreachable 0 0
Packet Too Big 0 0
Time Exceeded 0 0
Parameter Problems 0 0
Echos 0 0
Echo Replies 0 0
MLD Queries 0 0
MLD Reports 0 0
MLD Dones 0 0
Router Solicitations 0 26
Router Advertisements 0 0
Neighbor Solicitations 1 9
Neighbor Advertisements 3 10
Redirects 0 0
Router Renumberings 0 0

TCP Statistics for IPv4

Active Opens = 8324
Passive Opens = 157
Failed Connection Attempts = 145
Reset Connections = 692
Current Connections = 28
Segments Received = 508030
Segments Sent = 393377
Segments Retransmitted = 1554

TCP Statistics for IPv6

Active Opens = 58
Passive Opens = 14
Failed Connection Attempts = 44
Reset Connections = 2
Current Connections = 0
Segments Received = 671
Segments Sent = 583
Segments Retransmitted = 88

UDP Statistics for IPv4

Datagrams Received = 110188
No Ports = 4706
Receive Errors = 5
Datagrams Sent = 67974

UDP Statistics for IPv6

Datagrams Received = 3811
No Ports = 1456
Receive Errors = 0
Datagrams Sent = 3278

[cashmax]

Well regarding the cable, as mentioned earlier, without testing the frequency it's very hard to tell. Don't be put off by the flat cable, lots of them are, so if it says cat6 on the cable it probably is.

Re the connection speed - I can tell you that Gigaclear are unlikely to be able to solve the slow connection speed because it's not their issue and neither can they control it, the issue is on your side of the router and as soon as you the figure out that you get more speed from the wifi than the lan connection they will know this. Either way, if you have a 1000mbps connection direct to your laptop with a single cable then you should be getting much more speed than the wlan.

[TonyRPH]

S6PNJ said:

Tony, I missed your comment earlier - I was doing a quick reply over lunch - and cashmax, no I can understand the output fine thanks (I think). The connection is in my local village hall and I've not had the opportunity to do any further testing - maybe tomorrow... but on my home network, netstat -s shows me 24 received address errors out of 618099 packets received (IPv4), 0 under IPv6 (only 309 packets received), no errors under ICMPv4, 5 receive errors for UPD for IPv4. But this is all by the by as its a simple cable I want to test, not the internet link via FTTP/Gigaclear.

Try netstat -e any errors there will more than likely be (hardware) errors caused by the connection between your PC and router (IIRC)

So if you have a dodgy network card (very possible if RealTek - there were issues with the driver for a while) and also if you have a speed or duplex mismatch those errors will be reported too.

EDIT: You can also run it continuously with 'netstat -e 2' (will update at 2 second intervals) - this is useful to try during a large file transfer as any errors will usually manifest themselves right away.

Edited by TonyRPH on Thursday 7th November 10:31