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A Technical Question About the Internet, Routers, and WLAN

gumboot

lorcutus.tolere
gumboot
Joined
Jun 18, 2006
Messages
25,327
Okay, I have a query for anyone pretty familiar with home networks.

There appears to be a dramatic discrepancy in my internet speed on my desktop PC connected via LAN to my router and the speed on my laptop and media PC, connected via WLAN. The WLAN connection speed is actually faster than the LAN connection speed.

Based on a few tests I've done, and the wild different in download performance (14Mbps versus 2Mbps) my assumption is that my wireless router is for some reason limiting my internet speed via WLAN.

Is anyone familiar with this sort of thing, and can they suggest any alternative potential explanations or some solutions? I can't find any sort of setting in my router menu which would suggest slower performance via WLAN.
 
Clutching at straws somewhat, but how long is the cable, and is it running near or alongside any others? Clutching at straws since I've certainly used 20m cables without ill effect.
 
Did you do your tests for the different connections on a single machine?
Tried a different cable, too?

And, no, it doesn't sound familiar at all...
 
I'd be inclined to think that either a) software on your desktop PC is bogging things down (such as some sort of malware) or b) there's something wrong with the networking hardware in either the PC or the router - the wired hardware may be failing independently of the wireless.

Also, how long have you had your router? They unfortunately don't last forever; I had to replace mine just yesterday. Anecdotally, I've gotten about 5 years out of one DSL router before failure (Cisco) and 3 years out of my most recent one (Motorola).

My troubleshooting suggestions would be:
1. Run full scans with your antivirus/antimalware application(s) to ensure there are no software issues.
2. If you have access to them, try a wireless USB dongle and/or an Ethernet expansion card in the affected PC. Both can be found cheap or you may be able to accomplish this at a local computer repair shop.
3. Get a new router from your broadband provider. If you're having problems, they should provide this either free or for a nominal charge (depending on whether you own your hardware or lease it).
 
gumboot said:
Okay, I have a query for anyone pretty familiar with home networks.

There appears to be a dramatic discrepancy in my internet speed on my desktop PC connected via LAN to my router and the speed on my laptop and media PC, connected via WLAN. The WLAN connection speed is actually faster than the LAN connection speed.
Based on a few tests I've done, and the wild different in download performance (14Mbps versus 2Mbps) my assumption is that my wireless router is for some reason limiting my internet speed via WLAN.

Is anyone familiar with this sort of thing, and can they suggest any alternative potential explanations or some solutions? I can't find any sort of setting in my router menu which would suggest slower performance via WLAN.
Click to expand...

I've read this one. I've read this thrice but I still don't know what your problem is. The two high-lighted sections above appear to be contradictory. :(
 
Agree with Gord in Toronto - I think you have a typo and meant to say your WLAN is faster than your wired LAN.

What model is the router? There should be no rate-limiting by default.

Is there anything else plugged into your Wired LAN? Or is your desktop plugged directly into the router?

My suspicions, in decreasing order of suspicion, are:

- Incorrect speed/duplex settings on your router LAN interface and or desktop LAN interface
- Old or Incorrect drivers on your desktop NIC
- A bad ethernet cable
 
Sir drinks-a-lot had a good point.

Check duplex settings. They should both be set to either full or auto typically. Basically they need to all match. If one is set for auto and the other full then you will have issues.

The problem is that one end sets up the auto negotiation and if the other side is set to full it won't participate. This causes the auto negotiation to fail and the side configured for auto will fall-back to half duplex leaving you with half/full resulting in collisions at higher volumes of traffic.

I'm not sure if that makes sense, but the basic point is check the duplex settings and match them up.
 
Just to clarify; I'm talking about two separate connections here. One in the LAN/WLAN speed, which is the network connection speed. The other is the actual internet connection speed the computer is getting (via using an online speed test site).

The LAN and W/LAN base connection appears to be at maximum capability for the router; 100Mbps for the LAN and 150Mbps for the WLAN. I have no issues transferring files between computers over the network (actual transfer speeds are obviously typically less than the maximum, but I seem to generally get close to 100Mbps).

However the DSL speed via LAN is 14Mbps and the DSL speed via WLAN is 2Mbps.

I've used three machines, all with the same O/S, same anti-virus software, and similar performance specs.

Desktop is only LAN.
Mediabox is only WLAN.
Laptop can be WLAN or LAN. WLAN it gets 2Mbps DSL (same as the Mediabox) but LAN it gets 14Mbps DSL (same as the desktop).

I am perplexed as to the cause of this. It would seem that the router is deliberately slowing down internet traffic via WLAN, but I've never heard of this happening, and don't understand why it would do this, particularly given the maximum rated speed for the WLAN is higher than for the LAN (so if you were going to limit DSL via one, it would be the LAN, surely?).

The desktop and mediabox are both relatively new systems (3 years old, but both top of the line when they came out), the laptop is less than one year old, and both the router and the wireless adapter being used on the media box are brand new.

The only other thing that I can think of is absurdly obvious; something like it's encrypting the data via WLAN therefore all data transfer is slower, and this is to be expected. Hence why I asked if anyone else is familiar with this.

Perhaps on this note, does anyone know of any good free programmes that can be used to test the actual transfer speed via the network, in the same way that websites can test DSL speed?

In theory, if the router is slowing down traffic it should slow down all traffic, in which case the actual transfer speed over the network via WLAN should also be slower than via LAN.
 
gumboot said:
Just to clarify; I'm talking about two separate connections here. One in the LAN/WLAN speed, which is the network connection speed. The other is the actual internet connection speed the computer is getting (via using an online speed test site).
Click to expand...
Wow, I really needed that clarification because I was completely wrong about what I thought your problem was.

FTR, I have zero idea what's causing your slowdown and no idea how to diagnose it.
 
My understanding is that wireless uses Carrier sense multiple access with collision avoidance (CSMA/CA) rather than the ethernet Carrier Sense Multiple Access Collision Detect (CSMA/CD).

CSMA/CA is slower generally speaking; the collision avoidance part means there are more pauses between bursts of communication via wireless transmissions than with a wired transmission which is more aggressive in detecting collisions and retransmitting lost or collided data packets.
 
The Norseman said:
My understanding is that wireless uses Carrier sense multiple access with collision avoidance (CSMA/CA) rather than the ethernet Carrier Sense Multiple Access Collision Detect (CSMA/CD).

CSMA/CA is slower generally speaking; the collision avoidance part means there are more pauses between bursts of communication via wireless transmissions than with a wired transmission which is more aggressive in detecting collisions and retransmitting lost or collided data packets.
Click to expand...



Thanks Norseman. Moving on from this, do you know much about the difference between advertised transfer speeds and actual speeds? It would seem to me that in the above scenario you described a manufacturer would be required to advertise the wireless as slower than the wired? Obviously their specs exaggerate performance because they can't account for the speed at which data is coming off the computer and various other factors specific to the user's setup (cable quality, wireless range, blah blah), but surely if the way their hardware actually processed the data affected the speed they would have to take this into account?

In other words, if they advertised the WLAN as 150mbps and the LAN as 100mbps wouldn't that have had to take into account the difference in collision avoidance/detection, since that's a factor inherent in their hardware, not in the user's setup?
 
Most ISP-supplied routers these days I've come across have encryption enabled (WPA2/WPA) as standard. Shop bought ones may not; you'll probably have to set that up manually, or via a setup CD. But there are so many variables to consider I wouldn't like to suggest too much without knowing more about the current configuration. As the poster above mentioned, though changing the radio channel may help, if the problem is related to interference from another router (across the street, upstairs, next door; that sort of thing).
 
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I would try toggling off WMM (Wireless MultiMedia extensions) if the option exists.
 
gumboot said:
Thanks Norseman. Moving on from this, do you know much about the difference between advertised transfer speeds and actual speeds? It would seem to me that in the above scenario you described a manufacturer would be required to advertise the wireless as slower than the wired? Obviously their specs exaggerate performance because they can't account for the speed at which data is coming off the computer and various other factors specific to the user's setup (cable quality, wireless range, blah blah), but surely if the way their hardware actually processed the data affected the speed they would have to take this into account?

In other words, if they advertised the WLAN as 150mbps and the LAN as 100mbps wouldn't that have had to take into account the difference in collision avoidance/detection, since that's a factor inherent in their hardware, not in the user's setup?
Click to expand...

Well, to be honest, I have no idea what the advertising requirements would be. I'm guessing the hardware is advertised as all others are advertised -- "maximum values, your rates may vary due to blah de blah blah..."

The collision detection/avoidance is just one factor in networking... the signal strength, distance to base, noise or other interference, and then comes the hardline (the presumably copper cables to the DSLAM) for DSL service or if you're lucky the fiber optic cable to your ISP then you have to deal with the different protocols that ISP's use, the backbone congestion, "buffer bloat", and on and on.

As mentioned above, as far as locally speaking, changing the channel can really speed up your wireless speeds; the type of encryption isn't enough of a factor to affect speeds to my knowledge. Your computer modem *might* be old enough it doesn't support the newer speeds, though you may have already mentioned that and I missed it.

At this point, if it were me, I'd go into your NIC settings and make sure IPv6 is turned OFF. Also, I'd set your DNS to a static DNS server like opendns. IPv6 is not widely supported yet, and with Windows at least, I've noticed a significant delay while Windoze checks IPv6 connections before falling back to IPv4.

The last two things I mentioned I suggest for everyone's computer, be they wired or wireless. Just help speed up internet connectivity in general.

I've specialized in networking in school, though offhand I can't think of anything else that hasn't already been mentioned. I'll keep half a brain lobe out and post more if I think of it.
 
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