What can cause 38Mbps connection speed to drop to 27Mbps?

November 14, 2015 at 08:20:31
Specs: Windows 10, i5 4GB
My fiber 40Mbps broadband was giving me 38Mbps wifi. But suddenly its dropped to 27Mbps. I get 27Mbps on laptop, PC, iPhone and tablet. What could have happened and how do I fix it?

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#1
November 14, 2015 at 08:35:02
Try a simple reboot (power off completely the router, wait a couple of minutes, power on again).

What is service like on ethernet/cat-5 conection?

Have you checked with your isp to verify they are sending you the level you had previously over the fibre? It may be that incoming has dropped?


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#2
November 14, 2015 at 10:00:56
Power off and on was the first thing I tried. I cant connect wired as my pc is too far away and my laptop does not have a Lan socket, its an ultrabook! I have a usb/Lan plug but its USB 1 so is very slow, only good for admin.

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#3
November 14, 2015 at 10:49:21
mmm... Even the usb/lan adapter would allow you to login to the admin page(s) of your router; as would wifi of course... Both methods ought to show in status area current incoming signal strength - i.e. what Mbps is incoming from the isp.

If that figure is less than it ought to be... then suggest time to chat to your isp?


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Related Solutions

#4
November 14, 2015 at 17:16:01
I had a noisy line which BT fixed and tested the line at 40 mbs.down and 2 mbs up.

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#5
November 14, 2015 at 17:39:39
Poster is on fibre which "normally" doesn't suffer as much as copper with corrosion etc; presuming it's fibre all the way jnto the house and its connection point.

But... if the entry into the house is actually a copper link (fibre to copper connection) then it "might" be suffering with corrosion etc... In the UK at least the majority of "fibre" ccts. are usually a cpoper end into the house. Only very new installations may get fibre all the way. Similarly with (Virgin) cable systems...

I've had the similar issues as jOhn52 - with a seriously corroded copper cct. into the house (standard copper all the way, non-fibre dsl service). BT who service almost the entire broadband system in the UK replaced it of course with fresh copper...


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#6
November 14, 2015 at 19:21:53
My fiber 40Mbps broadband was giving me 38Mbps wifi. But suddenly its dropped to 27Mbps.

Are you talking about internal or external connectivity here? I suspect external which would mean you performed a bandwidth test online. Is this correct? If not, how then are you checking your bandwidth? If you are using an online bandwidth tester, are you testing during peak, or non-peak hours?

If during peak usage hours, consider that your bandwidth test can, and will be affected by total amount of traffic on the server you're testing on as well as traffic between the server and you. Do bandwidth test during peak hours and you're likely to get a lower reading than if you did it during off-peak hours.

Also, keep in mind that wireless never performs as well as wired network connections. This is due to wireless' inherent susceptibility to lag and latency. Overall, one can expect (on average) to achieve about 85% of their rated bandwidth. The other 15% gets used up in overhead. So to me, 38 Mbps is unusually high for a 40 Mbps rated link.

In my estimation, a 27 Mbps wireless connection is about what I'd expect on a 40 Mbps link. If you consider overhead, a wired connection should be getting (again, on average) about 34 Mbps and I would expect wireless to be significantly less than that.

It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.

***William Henley***


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#7
November 15, 2015 at 02:06:33
I had 38 mbs over wifi for over a year then it suddenly dropped to 27 mbs. I am wondering if this could be due to interference from neighbours who are all with BT and were on channel 1, but I see that many of them have changed to channel 6 which is my primary channel and 10 secondary as we run dual band N. None of the BT wifi's are dual band. 6 was clear for many months, as was 10. Perhaps I should change channels. However the neighbouring signal strengths are at least 20db down on mine, in the -80db to -90db range.

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#8
November 15, 2015 at 05:14:26
It could definitely be interference. Especially if you're all on the same channel. You should try a channel with less traffic.

It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.

***William Henley***


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#9
November 15, 2015 at 16:21:33
Is there no auto-channel selection on your modem/router? That should select a "free" channel for you.

Some wireless telephone sets are using the 2.4 GHz WI-FI band. Possible interference from this devices.

What bandwidth does your portable show for the WI-FI adapter?
If you move closer to the router, still the same bandwidth?


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#10
November 16, 2015 at 11:58:28
Channels 1, 6 & 11 give minimum overlaps, see here3:
http://www.moonblink.com/store/2poi...

I necessary use your router to chose one that avoids other users with the highest signal strengths.

I have found that the automatic setting often gets it wrong. Our next door neighbour is always unplugging his router, which restarts his auto channel search. As often as not it choses ours (we have no other near neighbor).

Always pop back and let us know the outcome - thanks


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#11
November 16, 2015 at 12:21:16
Just checked the channels around me and those that were on 6 have gone back to 1.
So 6 and 10 are just me. Still getting 10ms ping and 27 mbs down and 1.8 mbs up.
Hm.

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#12
November 16, 2015 at 12:59:42
I know you've stated your PC is a long way from your router but couldn't you borrow a long enough cable just to test?

If you did, and the wired wasn't getting the bandwidth you're paying for, then a call to your ISP would be the next step. But if however you were getting 40 Mbps (or 85% of that at least) with a wired connection and still only getting 27 with the wireless, I'd consider that good as per my statements above regarding wireless' overall performance.

Did you perchance change anything around the time of the drop? Did you maybe upgrade the firmware on the router?

Other than that, the only thing I can think of is perhaps the radio(s) in the router are having issues (hardware problem).

It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.

***William Henley***


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#13
November 16, 2015 at 13:31:52
Re #11

"6 and 10 are just me"
Except that 10 has overlaps.

However, I take the general point you are making, that choice of channel is unlikely to be significant in terms your issue.

Always pop back and let us know the outcome - thanks


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#14
November 16, 2015 at 13:45:30
Auto everything is off. I trialled the auto update with TalkTalk and it forced the wifi to channel 1 even though all my neighbours with BT were also on channel 1. I cut that off and set channel 6 as primary. I do a lot of tech trials for TalkTalk as I have been in telecoms for 36 years! Unfortunately wifi did not exist when I was at uni.

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