Functional Bandwidth not matching speed tested or advertised bandwidth

[archimago42]

I have a few questions about home networking but I'll ask my title question first and try to be as organized as possible.

I pay for fast internet (Comcast Blast! 50mbps download speed). I am receiving that internet when I connect directly to my modem or when I wire directly into my router (55mbps average download speed with a direct connection). My router is a Linksys N600 Dual Band Wireless router WNDR3400. My modem is approved for the speed I have (and seems to work) and is rented from Comcast.

My issue is that when I download files I've noticed a severe slow-down on the laptop that is doing the download (I haven't run simultaneous tests with other machines yet). With a download rate of approximately 1.6mbps I get a total slowdown of other services and get a speedtest.net rate of .6mbps. This is over wireless and this computer has the highest lose-rate for wireless with only 24mbps average on speedtest.net. That being said, it seems like 22.4mbps of download speed evaporates as soon as I download a file. I know that the file's source could be a limit on the download speed (the 1.6mbps) but that doesn't seem to explain why youtube and speedtest.net and the internet generally grinds to a halt when I use a very small fraction of my available bandwidth?

The problem is that I pay for this level of internet speed because I don't want to encounter slowdowns when I download something. If it was running at 24mbps, I'd understand it has used the full capacity this laptop seems to get on wireless, but it isn't even close.

What is going on here?

 

[fyrye]

What laptop/wireless adapter do you have?
What all have you done to resolve the issue?
Do you have any other devices you can test wireless connectivity with?
You said you have a Linksys N600, but the model you gave "WNDR3400" is for Netgear, is it a netgear router?

Considering when wired you are getting ~55Mbps, but wireless you are not puts blame on your wireless configuration.
Many things can become a factor such as interference, wireless adapter drivers, and software on your PC. With that said if your adapter is a 802.11b/g you won't get 802.11n speeds. If your adapter only supports 2.4ghz it won't connect at 5ghz.
802.11b = ~11Mbps
802.11g = ~22Mbps - 54Mbps
802.11n = ~54Mbps - 600Mbps

If you don't have another device to validate the adapter is at fault, there a few things you do to help improve your wireless performance. Test your speed after each step.
If the comcast modem is a gateway (modem, router/wireless router) disable the wireless radio on the modem.
Ensure the modem is plugged into the router's WAN port.
Update the drivers of your wireless adapter from the manufacturer's website.
Update the Firmware for the Netgear N600 router.
Change your wireless router channel usually best on channel 1, 3, or 5
Change your wireless router frequency width to 20 mhz/40 mhz or 40 mhz
Change your wireless router frequency rate from 2.4ghz to 5ghz
Disable QoS services on the router.

As far as cable speed is concerned, your speed will vary depending on time of day and demand on your cable's network block.
Cable is shared, so a high demand in your neighborhood will affect your connection. This usually isn't very noticeable. Other factors also affect your cable speed, such as signal strength etc. To which should all have been tested during installation, however rain and moisture can cause intermittent issues if the installation was done poorly (non-compression fittings, etc).

 

[archimago42]

What laptop/wireless adapter do you have?
What all have you done to resolve the issue?
Do you have any other devices you can test wireless connectivity with?
You said you have a Linksys N600, but the model you gave "WNDR3400" is for Netgear, is it a netgear router?

Considering when wired you are getting ~55Mbps, but wireless you are not puts blame on your wireless configuration.
Many things can become a factor such as interference, wireless adapter drivers, and software on your PC. With that said if your adapter is a 802.11b/g you won't get 802.11n speeds. If your adapter only supports 2.4ghz it won't connect at 5ghz.
802.11b = ~11Mbps
802.11g = ~22Mbps - 54Mbps
802.11n = ~54Mbps - 600Mbps

If you don't have another device to validate the adapter is at fault, there a few things you do to help improve your wireless performance. Test your speed after each step.
If the comcast modem is a gateway (modem, router/wireless router) disable the wireless radio on the modem.
Ensure the modem is plugged into the router's WAN port.
Update the drivers of your wireless adapter from the manufacturer's website.
Update the Firmware for the Netgear N600 router.
Change your wireless router channel usually best on channel 1, 3, or 5
Change your wireless router frequency width to 20 mhz/40 mhz or 40 mhz
Change your wireless router frequency rate from 2.4ghz to 5ghz
Disable QoS services on the router.

As far as cable speed is concerned, your speed will vary depending on time of day and demand on your cable's network block.
Cable is shared, so a high demand in your neighborhood will affect your connection. This usually isn't very noticeable. Other factors also affect your cable speed, such as signal strength etc. To which should all have been tested during installation, however rain and moisture can cause intermittent issues if the installation was done poorly (non-compression fittings, etc).

Thanks for the detailed response. I did make an error and I meant Netgear and not Linksys. I also hopefully just solved the issue, so I'll tell you what I've done.

I have a Dell Wireless 1510 Wireless-N WLAN Mini-Card. (http://wikidevi.com/wiki/Dell_Wireless_1510_Wireless-N_WLAN_Mini-Card) It seems to be fully capable of N speeds. Windows says the drivers are fully updated. Ah, but then I compared the firmware versions and it was not up to date. I also updated my router's firmware (which I had forgotten I reset it a week or two ago and hadn't updated again).

After updating the firmware I think my desktop (an alternate and much more powerful computer) was getting slightly higher speeds (consistent 50-55mbps wireless when I had in the 40s before), but this laptop (Dell Latitude E6400) was actually doing even worse. It was shakily pulling 9-13mbps on speedtest.net. So, I updated the drivers for my card and restarted and now it is pulling 50+mbps as well.

I disabled WMM in the QoS settings when I upgraded the firmware for the router, so that also could have played some role (but I have done that in the past before I reset it so I don't think it was the whole solution). I've also checked inSSIDer 3 to try to get the best channels I can. I'm on 11 for the 2.5g and there are no other 5g networks in my area, so I'm on whatever it is on with no interference.

One other thing I wanted to ask though, is that I get way worse signal strength from my 5G band than my 2.5g band on my router and I was wondering if there is anything I can do about that? It is sometimes half as powerful, even though it has no competing 5G networks. I feel like its strength has dropped over the last two years I've had it but I can't be sure of that. Any thoughts on that? I don't have a huge apartment and it is losing a lot of strength from one end to the other.

Thanks for your help. It turned out to be a relatively simple problem, but it took another reminder to make me actually manually check the versions of my drivers.

 

[fyrye]

Yea driver's are usually the case, especially when it comes to drivers provided by microsoft vs the manufacturer.

This article may help you in regards to your question about 2.4ghz and 5ghz.
http://www.linuxplanet.com/linuxplanet/reports/6581/1/


If there are only 1 or 2 people in your area, I'd set it to around 1, 3, or 5. This will ensure you get the most range. If you notice a decline in your signal quality, then increase it incrementally. Start low and work your way up.
Some routers also allow you to increase the transmit rate/power of your router, by increasing the power number you generally get better range (depending on antenna installed). Doing so however will decrease the life of your router as does most things overclocking.
As a side note the Tx power is for the most part already set by the manufacturer at an optimal level for the installed antenna, and increasing it won't do much if anything
You will notice a steady decrease as you lower it below 50, but as you increase it above 70-200, little to no difference in signal will occur.
http://tomatousb.org/tut:increasing-wrt54g-transmit-power

As a general rule of thumb, higher frequency means less range. Sounds backwards, but radio waves attenuate differently at higher frequencies, meaning they won't last as long in certain conditions.

Could you mark the topic as solved please so that others looking for similar support will also check their drivers?