X40 with 802.11b/g can't connect to g-only network -- why?

[tbessie]

Hey all...

So I set my wireless router to be "G Only", and for some reason the 802.11b/g card in my X40 won't connect to it, even though it sees the network. When I switch to "mixed mode" or "B only", it works.

Could be the router, but other G-only devices work fine... does anyone know if there are only a limited set of channels, for example, that the 802.11b/g cards IBM/Lenovo uses, provides? I've switched channels a few times to check, but it makes no difference.

- Tim

[sugo]

There are intel and atheros b/g cards for X40. Which one do you have? Are you using Access Connection or Windows to manage the wireless connection?

[tomh009]

Hey all...

So I set my wireless router to be "G Only", and for some reason the 802.11b/g card in my X40 won't connect to it, even though it sees the network. When I switch to "mixed mode" or "B only", it works.

Could be the router, but other G-only devices work fine... does anyone know if there are only a limited set of channels, for example, that the 802.11b/g cards IBM/Lenovo uses, provides? I've switched channels a few times to check, but it makes no difference.

Are you switching channels on the router or on the X40? You should leave the X40 on auto (assuming it has a channel selection). How is the network secured? None, MAC address, WEP or WPA?

I would suggest downloading network stumbler: http://www.netstumbler.com/downloads/

Run it to take a look and see what channel each of the networks around you are, and whether they might be interfering. Remember that with 802.11b/g, the channels overlap, and you really need to be five channels away to minimize crosstalk. Hence the non-overlapping channels are usually considered to be 1, 6 and 11.

[tbessie]

There are intel and atheros b/g cards for X40. Which one do you have? Are you using Access Connection or Windows to manage the wireless connection?

It's an Atheros card, and I'm using Access Connections -- take a look below, though, I found what the problem was; it wasn't intuitive.

- Tim

[tbessie]

Hey all...

So I set my wireless router to be "G Only", and for some reason the 802.11b/g card in my X40 won't connect to it, even though it sees the network. When I switch to "mixed mode" or "B only", it works.

Could be the router, but other G-only devices work fine... does anyone know if there are only a limited set of channels, for example, that the 802.11b/g cards IBM/Lenovo uses, provides? I've switched channels a few times to check, but it makes no difference.

Are you switching channels on the router or on the X40? You should leave the X40 on auto (assuming it has a channel selection). How is the network secured? None, MAC address, WEP or WPA?

I would suggest downloading network stumbler: http://www.netstumbler.com/downloads/

Run it to take a look and see what channel each of the networks around you are, and whether they might be interfering. Remember that with 802.11b/g, the channels overlap, and you really need to be five channels away to minimize crosstalk. Hence the non-overlapping channels are usually considered to be 1, 6 and 11.

Hi Tom...

Actually, I've got a WiSpy (cheap frequency scanner), and I moved over to Channel 11 because it seemed less used nearby. I'm using the X40 on 'g-only' for my Access Connections "Home/Wifi" profile, since I set the router to be g-only -- at least, that would seem to make sense. I tried Auto, incidentally, but that didn't fix it.

The network is secured both my MAC and by WPA2/AES, which I would *hope* would be enough; I'm using a static IP from the X40, although could also use DHCP and have the router assign MAC->IP... both worked. Is one considered more secure?

Incidentally, this loss of connection happened when I switched from WEP-128/Mixed-mode to WPA2/g-only. I'm not sure what the interactions are between encryption and 802.11 version, though.

In any case, I discovered what the problem was - for some reason, when I set the "802.11b preamble" to "Short & long" instead of "Long only", it connected. I wonder why that would make a difference, since I'm not using 802.11b, but 802.11g (I am aware that a g device can function on a b network).

Do you know what this signifies? I'll go research what this preamble thing is in any case.

Thanks for all your suggestions and help!

- Tim

[tomh009]

Actually, I've got a WiSpy (cheap frequency scanner), and I moved over to Channel 11 because it seemed less used nearby. I'm using the X40 on 'g-only' for my Access Connections "Home/Wifi" profile, since I set the router to be g-only -- at least, that would seem to make sense. I tried Auto, incidentally, but that didn't fix it.

The network is secured both my MAC and by WPA2/AES, which I would *hope* would be enough; I'm using a static IP from the X40, although could also use DHCP and have the router assign MAC->IP... both worked. Is one considered more secure?

Incidentally, this loss of connection happened when I switched from WEP-128/Mixed-mode to WPA2/g-only. I'm not sure what the interactions are between encryption and 802.11 version, though.

In any case, I discovered what the problem was - for some reason, when I set the "802.11b preamble" to "Short & long" instead of "Long only", it connected. I wonder why that would make a difference, since I'm not using 802.11b, but 802.11g (I am aware that a g device can function on a b network).

Do you know what this signifies? I'll go research what this preamble thing is in any case.

Basically 802.11 uses a preamble for the two ends of the connection to sync before a packet transmission. Short preamble generally improves performance. On which end did you need to make this change? On the X40?

The encryption should be independent of the transmission speed/band.

[tbessie]

Actually, I've got a WiSpy (cheap frequency scanner), and I moved over to Channel 11 because it seemed less used nearby. I'm using the X40 on 'g-only' for my Access Connections "Home/Wifi" profile, since I set the router to be g-only -- at least, that would seem to make sense. I tried Auto, incidentally, but that didn't fix it.

The network is secured both my MAC and by WPA2/AES, which I would *hope* would be enough; I'm using a static IP from the X40, although could also use DHCP and have the router assign MAC->IP... both worked. Is one considered more secure?

Incidentally, this loss of connection happened when I switched from WEP-128/Mixed-mode to WPA2/g-only. I'm not sure what the interactions are between encryption and 802.11 version, though.

In any case, I discovered what the problem was - for some reason, when I set the "802.11b preamble" to "Short & long" instead of "Long only", it connected. I wonder why that would make a difference, since I'm not using 802.11b, but 802.11g (I am aware that a g device can function on a b network).

Do you know what this signifies? I'll go research what this preamble thing is in any case.

Basically 802.11 uses a preamble for the two ends of the connection to sync before a packet transmission. Short preamble generally improves performance. On which end did you need to make this change? On the X40?

The encryption should be independent of the transmission speed/band.

I needed to make the change on the X40.

This link seems to imply that it's required for g-only networks:

http://www.tomsnetworking.com/2003/02/05/802/page5.html


- Tim

[tomh009]

This link seems to imply that it's required for g-only networks:

http://www.tomsnetworking.com/2003/02/05/802/page5.html

Excellent link -- I have learned something today. Thanks!