cancel
Showing results for 
Search instead for 
Did you mean: 

Slow internet on one PC of wireless network

DrSeeAll
Grafter
Posts: 51
Registered: 30-07-2007

Slow internet on one PC of wireless network

I've got four PCs wirelessly networked (using 8.02b). On three of them I get good speeds (~470kbps on a 512k connection) but on the fourth I only get about 150kbps. This PC is the farthest from the WAP (Dell Truemobile) but the signal strength is still "excellent" -70dBm. Ping time to the WAP is about 4ms. I'm using an Actiontec USB Adapter. If I connect this PC directly to broadband using a USB cable/modem then I get good speed too.

Is it purely the distance (about 15m) that is causing the reduced speed even though the signal strength is reported as "excellent"? If so, can someone explain the technical reason why that should be. I could understand it if the signal was marginal.
Is there anything I can do about it?

If I use my laptop at the same location as the 4th PC the signal is only -25dBm but the speed remains excellent!!??


BTW the signal to this 4th PC has to travel outside and connection speeds are even worse when it is raining , as if the signal is attenuated even further (it still remains "excellent" though). There is no other wireless network nearby causing interference.

I'm puzzled. Suggestions, anyone?
TIA
12 REPLIES
DrSeeAll
Grafter
Posts: 51
Registered: 30-07-2007

Slow internet on one PC of wireless network

Hasn't anyone got any suggestions?
Further information. Over the weekend I've been running the ADSL speed test and it consistantly says my upload speed (250kbps) is better than my d/l speed (between 150 and 200kbps) when I'm using the wireless connection.

If I connect this PC directly to the modem by cable then the d/l speed is trebled to about 470kbps. It seems the wireless connection is somehow throttling the d/load - but only on this one PC.

I would be grateful for any advice as this PC is my main one.
chris2172
Newbie
Posts: 4
Registered: 04-08-2007

Slow internet on one PC of wireless network

Some WAP's can be configured to throttel bandwith over MAC addresses, could this be the case with your WAP?

Secondly has your computer got a built in network card that is enabled causing the lag on DNS lookup as it attempts to do a lookup through the RJ45 first? if so disable it.

Hope this is of some use

Regards
Chris
DrSeeAll
Grafter
Posts: 51
Registered: 30-07-2007

Slow internet on one PC of wireless network

I've got the WAP set up with DHCP enabled and the four MAC addresses of each PC reserved.
There doesn't seem to be any option to throttle bandwith at all and certainly not one MAC address in preference to the others.

I do have an ethernet card but that is already disabled.

Thanks for your reply. Any more suggestions?

Cheers
chris2172
Newbie
Posts: 4
Registered: 04-08-2007

Slow internet on one PC of wireless network

The only other sugestion I could think of it to swap the wireless cards over and see if the problem follows the card or the computer.

That would narrow the issue down a little

Regards

Chris
Community Veteran
Posts: 4,729
Registered: 04-04-2007

Slow internet on one PC of wireless network

I have found that the range and speed of my Dell TureMobile 1180 CF card to a D-LInk DSL-604+, is very poor. Some cards and AP's just do not work well together. Yet the ramge on the TureMobile to other AP's is not bad.

Also 70db is a poor signal, somewhere between 50 to 60db is the limit for good reception.

Also if the signal has to pass throght two outside walls that will not help range.

Chilly
DrSeeAll
Grafter
Posts: 51
Registered: 30-07-2007

Slow internet on one PC of wireless network

@Chris
I've already tried swapping the wireless cards. It does not make any difference. Strangely the first time I try a speed test after restarting the wireless adapter I sometimes get a good speed (>400kbps) but on subsequent occasions it drops down to less than 200kbps.

@chillypenquin
I think you are right. I think the Actiontec USB adapter and Dell Truemobile are not the best combination.
I've been experimenting with a homemade parabolic reflector (cardboard and tinfoil). This increases the signal strength a little and seems to give slightly better speeds.
It is difficult to get accuratce comparisions though as the PN Speedtest is gving me hugely variable results. Its after 1.00am so I suspect traffic is pretty light but four consecutive speed tests within a few minutes give these results
130
227
194
369kbps
without changing anything!
Would this indicate a signal strength problem? Its not raining and no one else is on my network.

Thanks for your help guys. This is a real puzzle.
Cheers.
N/A

Slow internet on one PC of wireless network

It may be worth checking that the MTU for that machine and adapter is within range.

I had a similar issue which I resolved by setting an TCP Receive Window of 13900 and a MTU of 1430 on the machine in question.

John
Community Veteran
Posts: 4,729
Registered: 04-04-2007

Slow internet on one PC of wireless network

I would try again with the WEP encryption turned off, see what effect that has.
The USB device would be reliant on CPU time to perform WEP encryption, and this may be causing the bottleneck.

What normally causes a slow down on wireless networks is a large number of dropped packets causing retries.

To monitor the connection using “ping” is more effective if you increase the number of bytes sent and the number of packets.

ping –n 100 –l 512 hostname


Will send 100 packets at 512 bytes each.

Also checkout the forums @ http://www.expansys.com/forumoverview.asp

Chilly
DrSeeAll
Grafter
Posts: 51
Registered: 30-07-2007

Slow internet on one PC of wireless network

@John
The TrueMobile WAP has fixed MTU of 1372 (it cannot be altered AFAIAA). I've configured the other adapters to 1372 too. (I've also tried lots of other values aswell) but it makes no difference.

@CP
All four PCs are on XP SP2 and are using WEP. I do not see why WEP would affect speed on just one and not the other three. Anyway, I've just tried your suggestion and disabled WEP on the "bad" PC and it made no difference so I've enabled it again.


To eliminate the distance/signal strength/outdoor/indoor problem, after a bit of effort, I've moved the whole WAP/modem into the same room as the "bad" PC. The aerials are 1m apart. Signal strength is 100% yet the average speed is just over 200kbps. If I connect directly to the modem by USB I immediately get an excellent 470kbps.

I've also tested multiple pings. I had to change the syntax to:-

ping hostname –n 100 –l 512

I get 100% transfer efficiency. No packets lost both with the normal positioning of the WAP and with the temporary close position.

It would seem that the problem lies with either the Truemobile AP or with the Actiontec USB wireless adapter. However, they both work fine with the other PCs on the network.

I'm running out of ideas.
Thanks for all your input so far. I would be grateful for any other suggestions.
DrSeeAll
Grafter
Posts: 51
Registered: 30-07-2007

Problem solved - I think!

Well after hours of messing I plugged the Actiontec USB wireless adapter into a USB port on the front panel of the PC (I'd previously been using those on the rear) and D/L speed is now consistantly good.
Cheesy
Why should there be a difference in USB ports performance from front to rear panels?
Cheers
Community Veteran
Posts: 4,729
Registered: 04-04-2007

Slow internet on one PC of wireless network

Glad you sorted it. It does seam that all USB ports are not the same.

Are the ports are based on the motherboard or an expansion card.

I had fun with a couple of SunBlade1500’s last week. With the keyboard and trackball plugged in the front all was fine. To tidy up the wiring I plugged the keyboard and trackball into the USB sockets at the bottom on the back. The French layout keyboards changed to English, and when I rebooted where not recognised at all. But plugging them into the USB socket at the top on the rear panel worked fine :roll:

Chilly
DrSeeAll
Grafter
Posts: 51
Registered: 30-07-2007

Slow internet on one PC of wireless network

@CP
The rear USB ports come directly from the motherboard. The front ones are part of a card reader panel. Its a Medion PC. Perhaps one set are USB1 and the others USB2? .... if that makes any difference?