Getting significant drop in speed in secondary router connected via CAT6 LAN Cable

[downloaderfan]

Hi All,

 

Recently I switched ISPs & now get a speed of 150 Mbps using the router they provided. However, the WiFi doesn't reach 2 rooms away, so I connected a 20 meter RJ45 Cat 6 cable to WAN port of this router kept in the other room. I was using this previously as my main router. Since it's a router than supports both 2.4 & 5 GHz bands, I was expecting to get full 150 Mbps on the other room as well on the 5 Ghz band. But on repeated tests over multiple days, the speed I got on the secondary router was 92 Mbps. That's about 40% drop in internet speed. 

 

Is this normal & is there something I can do to improve it? Why does this happen?

 

P.S : I tried connecting the other end of the RJ45 cable (the one connected to secondary router) to my laptop & was getting full 150 Mbps, so it's definitely not a faulty cable. 

[dj_ripcord]

What kind of router is your ISP giving you? 92mbps sounds like old 'fast ethernet' standard, which is 100mbps max.

 

Otherwise, my bet is on the cable being bad. If you bought it brand new, that's unlikely - but still a possibility.

[downloaderfan]

3 minutes ago, dj_ripcord said:

What kind of router is your ISP giving you? 92mbps sounds like old 'fast ethernet' standard, which is 100mbps max.

 

Otherwise, my bet is on the cable being bad. If you bought it brand new, that's unlikely - but still a possibility.

 

There is a primary router and a secondary router. Primary router (The one provided by ISP) gives me 150 Mbps on speed test. So def not limited to 100 Mbps. The secondary router is the 1 I linked in initial post, which is again not limited to 100 Mbps. Also on connecting the cable directly to my laptop instead of the secondary router, I am getting 150 Mbps. Thus the dilemma. Yes the cable is brand new.

[dj_ripcord]

6 minutes ago, downloaderfan said:

 

There is a primary router and a secondary router. Primary router (The one provided by ISP) gives me 150 Mbps on speed test. So def not limited to 100 Mbps. The secondary router is the 1 I linked in initial post, which is again not limited to 100 Mbps. Also on connecting the cable directly to my laptop instead of the secondary router, I am getting 150 Mbps. Thus the dilemma. Yes the cable is brand new.

Wow, interesting. Hopefully someone else can chime in. I already checked that secondary router on Amazon, and it does in fact have gigabit ports. So I am really bewildered here as to what could be amiss.

[Zando_]

What channel width is it running on the 5Ghz radio? You'll want it to be set to 80Mhz to go full zoom, I forget what 40Mhz ended up with in my testing, but 20Mhz tends to cap out around that 90-ish number IIRC (the Unifi APs I've messed with have 20, 40, and 80 as options for 5GHz). The lower channel width = better signal at range, but lower bandwidth. For the AP right above my office it's set to 80Mhz (as we don't need the range), I can pull 300-400 up/down fine on a mid-2015 MacBook Pro. 

[downloaderfan]

1 hour ago, Zando_ said:

What channel width is it running on the 5Ghz radio? You'll want it to be set to 80Mhz to go full zoom, I forget what 40Mhz ended up with in my testing, but 20Mhz tends to cap out around that 90-ish number IIRC (the Unifi APs I've messed with have 20, 40, and 80 as options for 5GHz). The lower channel width = better signal at range, but lower bandwidth. For the AP right above my office it's set to 80Mhz (as we don't need the range), I can pull 300-400 up/down fine on a mid-2015 MacBook Pro. 

I set the 5 Ghz to 80 MHz, still no dice. But I seem to have zeroed in on the problem. (Just not the solution, yet) In the TP-Link Archer A6 router page, it is showing negotiation speed for ethernet as 100 Mbps full duplex even though it is a gigabit router.

 

 

It's not the cable or port of primary router either as on directly connecting RJ45 to laptop instead of router, I am getting full 150 Mbps. Seems like a TP-Link firmware bug.

[Alex Atkin UK]

1 hour ago, downloaderfan said:

I set the 5 Ghz to 80 MHz, still no dice. But I seem to have zeroed in on the problem. (Just not the solution, yet) In the TP-Link Archer A6 router page, it is showing negotiation speed for ethernet as 100 Mbps full duplex even though it is a gigabit router.

 

 

It's not the cable or port of primary router either as on directly connecting RJ45 to laptop instead of router, I am getting full 150 Mbps. Seems like a TP-Link firmware bug.

Not necessarily, a bad cable can sometimes work at Gigabit on one device and not another.  Every network adapter has a difference tolerance for marginal cables, depending on exactly what it is about the cable that is faulty.

Its always worth trying a difference cable and also inspecting the sockets for bent pins, dust/dirt, etc.  Clean sockets and plugs with a Q tip and isoproplyl alcohol to make sure there is no containments on them.

Or even as simple as connecting the laptop to the WAN port you think is faulty and see if it links at Gigabit.

[downloaderfan]

8 hours ago, Alex Atkin UK said:

Not necessarily, a bad cable can sometimes work at Gigabit on one device and not another.  Every network adapter has a difference tolerance for marginal cables, depending on exactly what it is about the cable that is faulty.

Its always worth trying a difference cable and also inspecting the sockets for bent pins, dust/dirt, etc.  Clean sockets and plugs with a Q tip and isoproplyl alcohol to make sure there is no containments on them.

Or even as simple as connecting the laptop to the WAN port you think is faulty and see if it links at Gigabit.

 

Ok, I tried with another 3 meter ethernet cable whose RJ45 ports were machined and did not require separate crimping. On connecting that, I am indeed seeing 1000 Mbps as negotiation speed within TP-Link router page & getting the full 150 Mbps on speed test.

 

I am confused what is at fault here? The router? The Cable?

 

The cable is a new CAT 6 one from D-Link. I had a guy crimp RJ45 to it. I asked 2 different ethernet crimping guys about this, they said if the RJ45 port was not crimped to the wire properly, it wouldn't work at all, it doesn't occur that I would get internet at a lower speed. And then again, on connecting the laptop directly instead of the secondary router, I am getting full 150 Mbps. Also, after reading your suggestion, I did clean the WAN and LAN ports with Q tip and alcohol, still no effect. I also hard reset the firmware of the router, still the same.

 

I am confused what to do next. Last I had a call with TP-Link customer support, they took all the details, suggested me some troubleshooting steps that I had already tried prior due to googling & said that they would get back to me. Awaiting their call at the moment.

[Alex Atkin UK]

8 hours ago, downloaderfan said:

I had a guy crimp RJ45 to it. I asked 2 different ethernet crimping guys about this, they said if the RJ45 port was not crimped to the wire properly, it wouldn't work at all, it doesn't occur that I would get internet at a lower speed.

They are mistaken, the most common fault and you see it on this forum all the time, is getting 100Mbit due to not all pins making good contact, as 100Mbit only needs four wires whereas Gigabit uses all eight.

The second most common is what you have where all eight are connected but likely with a high resistance fault by the crimp making contact but not quite well enough, or bad cable, making it out of spec.  That's why some clients will handle it, others will not, as some will only operate if it matches the specifications perfectly whereas others will have some leeway.

 

There's unfortunately a lot of bad cables (particularly copper coated aluminium/CCA) sold as CAT6 that is not even close to spec.  I even had a pre-made CAT6a cable that worked at 5Gbit but not 10Gbit.

[Falcon1986]

19 hours ago, downloaderfan said:

I had a guy crimp RJ45 to it.

Good guys can make bad crimps sometimes. It happens to us all.

 

19 hours ago, downloaderfan said:

...they said if the RJ45 port was not crimped to the wire properly, it wouldn't work at all, it doesn't occur that I would get internet at a lower speed. And then again, on connecting the laptop directly instead of the secondary router, I am getting full 150 Mbps.

Well, your experience shows that that's not necessarily the case. Most times, it's a fault somewhere in the cable itself.

 

If you notice a situation where the negotiated speed changes dynamically when you swap out devices, that's also a sign of a faulty cable. Even little movements can change speeds, so something is obviously wrong.

 

19 hours ago, downloaderfan said:

Ok, I tried with another 3 meter ethernet cable whose RJ45 ports were machined and did not require separate crimping.

Lesson: even brand new cables can have faults. Pre-crimped ethernet cables of appropriate length from reputable brands are usually OK.

 

The solution might be hard to accept, but sometimes you just need a fresh new cable.

 

[downloaderfan]

14 hours ago, Alex Atkin UK said:

They are mistaken, the most common fault and you see it on this forum all the time, is getting 100Mbit due to not all pins making good contact, as 100Mbit only needs four wires whereas Gigabit uses all eight.

The second most common is what you have where all eight are connected but likely with a high resistance fault by the crimp making contact but not quite well enough, or bad cable, making it out of spec.  That's why some clients will handle it, others will not, as some will only operate if it matches the specifications perfectly whereas others will have some leeway.

 

There's unfortunately a lot of bad cables (particularly copper coated aluminium/CCA) sold as CAT6 that is not even close to spec.  I even had a pre-made CAT6a cable that worked at 5Gbit but not 10Gbit.

So what is the solution you recommend? Currently I'm planning to go to TP-Link service center which is on an hour drive, but it seems they would just connect a regular ethernet cable & see that I'm getting 1000 Mbps & shift the blame again. Should I call another guy and have this recrimp since this is a resistance issue?

[downloaderfan]

2 hours ago, Falcon1986 said:

Good guys can make bad crimps sometimes. It happens to us all.

 

Well, your experience shows that that's not necessarily the case. Most times, it's a fault somewhere in the cable itself.

 

If you notice a situation where the negotiated speed changes dynamically when you swap out devices, that's also a sign of a faulty cable. Even little movements can change speeds, so something is obviously wrong.

 

Lesson: even brand new cables can have faults. Pre-crimped ethernet cables of appropriate length from reputable brands are usually OK.

 

The solution might be hard to accept, but sometimes you just need a fresh new cable.

 

I guess, if I were to buy a new cable which was pre-crimped, I can still cut it have it re-crimped later right? I'm passing the wire through holes in my window through which RJ45 cannot fit. Thus the recrimping.

[Needfuldoer]

Take a close look at both ends of the cable that only gives you 100 meg. If the homemade end was done with EZ RJs (where the conductors poke through and a blade on the crimper cuts them flush), check the cut ends of the cables. I've seen that happen when the blade on the crimper was getting dull and mushroomed the wires instead of slicing them.

 

 

It could also be due to crosstalk or interference. I've seen that happen when a tight loop of cable gets pulled into a twist, throwing the balanced signals off. 

 

A good cable certifier would be able to tell you why a cable might be failing, but those are much too expensive to be worth it for just a single run. (Those little continuity testers with the lights that flash in sequence are only good for letting you know you got the wires in the right order.)

 

4 hours ago, downloaderfan said:

I guess, if I were to buy a new cable which was pre-crimped, I can still cut it have it re-crimped later right? I'm passing the wire through holes in my window through which RJ45 cannot fit. Thus the recrimping.

Absolutely. Just make sure you have the right ends and crimper, and the connector gets installed to spec.

[Alex Atkin UK]

9 hours ago, downloaderfan said:

I guess, if I were to buy a new cable which was pre-crimped, I can still cut it have it re-crimped later right? I'm passing the wire through holes in my window through which RJ45 cannot fit. Thus the recrimping.

Is this going outdoors then?  Make sure its rated for that if so or the outer sheathing will get destroyed by weathering.

 

Pre-terminated can be useful as you get to confirm its working fine from the factory.  Even if you have to crimp one end eventually, at least you know ONE end is done well. 

The nightmare is when you have problems and don't know which end is causing the issue or even if the cable was good to begin with.