Router throttling bandwidth

Posted on 2013-05-19
Last Modified: 2013-07-03
I have a dlink DIR-615 wireless router. For some reason when I have a connection wired or wireless through this device, my bandwidth is at about a fourth of what it should be. Both upload and download speeds are effected. Im pretty sure it isn't the modem or the ISP because if I connect my laptop directly into the modem, my speeds are perfect. Is there a setting on the router that I need to adjust? I change my wireless key as well so I know that nobody else is on my connection.
Question by:StarfishTech
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Assisted Solution

jpgobert earned 166 total points
ID: 39180058
Can you give a few more details on the numbers you're seeing?

What's your rated bandwidth?  What's the internet connection type?  What's your OS?  How are you testing your throughput?  What's the throughput (upload and download) that you're getting when you connect directly to the modem?  What's the throughput when you're connected to the d-link box?
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Assisted Solution

gheist earned 167 total points
ID: 39180697
Do you use any traffic shaping? Do you get SNMP numbers?
Is openWRT possible (like wondershaper)
Is problem on both wired and wireless?

Accepted Solution

corower earned 167 total points
ID: 39190608
StarfishTech: as you have not given any numbers on what are the links capabilities, the following is just a speculation. here (Riga, Latvia) we are used to _fast_ internet connections, 1G access ports for home users and FTTD are not rare, and "default" speed is 100M with slight shaping on the edge. and it's under 30$ altogether.

first of all - at these speeds cables (physical connection) matter a lot. if you have faulty connection/bad cable at some point, you may get bad connection and packet loss. check how your router negotiates with your ISP and with LAN. doublecheck autonegotiate speeds and duplex modes. check for packet loss to your router and to the ISPs gateway.
(@ windows - start command promt (start-run > cmd), then in this window run ping -t -l 14720 -n 1000 <ip>. leave the window for aprox.15 minutes . if your or ISPs router/gateway is not able to answer large pings, use 1472 instead of 14720. to get intermediate results use ctrl-break. to stop before end - ctrl-c.
@ linux/bsd - ping -s 1472 -c 10000 -f <ip> . )
if you have any packets lost - speed loss is only half of a problem here. duplex mismatch or transmission errors usualy give much higher error rate - around 7-10% at FE speeds. maybe your incomming ether line is a bit to long, or just noisy, and router hasnt enough juice to get past that (like - weak or underpowered networking subsystem. then you'll have to change that router.)

anyway - ping should show no lost packets at all. then links are OK, and the issue might be your router.
 try to download something big (like run some torrents) and ping at the same time. if picture changes dramaticaly, you see packetloss and large fluctuation in ping reply times -  your router seems to be the weakest link. the reason might be as simple as "not having enough horsepower". i seriously doubt, that this router is capable of keeping up at 100Mbit or more. after all - you said, that "speed is 1/4 of expected". i know, most of these routers are old broadbands, with just some facelifts like radio, with enough power to deliver only around 35-40 Mbits. for WiFi its even less, around 25M.

however, if your "expected" is around 10M, then router in no way should be the bottleneck. it definately has enough power to deliver at these speeds. login to router and check, if it has any advanced connection security enabled. that might impact throughput. there is an OpenWRT version specifically crafted for this router family, it is highly optimised, and might help if problem is bad firmware design (btw, have you updated original router firmware?). also under custom WRT image, you might see, if problem is routers CPU load or if there are receive/transmit errors on interfaces. this'll definately guide you towards solution.

also, check, if your router ir running cold or hot. many hardware vendors force routers to lowering procesisng speeds, if they're overtemp. case must be room temperature, or slightly warm at most.
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Expert Comment

ID: 39192461
Malatsis :)
But lets not hurry with assumptions. We need to knwo if he gets 10MBps or 10kbps first

Expert Comment

ID: 39198713
gheist pldz :)
if StarfishTech is stuck with low speeds - local issues should be solved first. and we need more data, anyway.

p.s. i doubt, requestor will ever get back to us. it's full week away already.

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