Just in the occasional coffee-shop . . . my wireless card (DWL-G650) never acquires a DHCP lease via dhcpcd.

In other places it works just fine.

I'm using the madwifi driver, usually without problems. The coffee shops in question are all, of course, in "managed" mode, without WEP or WPA. And what happens is that dhcpcd simply times-out. Doing some debugging, I don't see the usual exchanges happening at all.

What I'm really looking for is some kind of strategy for how to troubleshoot and resolve these problems. Assuming that one is familiar with the command-line .. with wlanconfig, iwconfig, ifconfig (any others?) .. how would one go about getting on-line?

Are there any subtle configuration-parameters that might be important at some coffee-shops?

And... is it reasonable to get "ad hoc" to work?

I've seen similar things and I've come to the conclusion that it might be more of a router/AP issue than anything. I'm frequently at a friend's house using his wireless connection. It is a D-link router that has been dumbed-down to be just an AP connected to a Linksys router which acts as the DHCP server. About 90% of the time, dhcpcd simply times out when I try to get and IP address. If my friend simply reboots the D-Link AP, then I pick up an IP without any trouble. What is really strange is that NONE of my friend's computers ever have an issue getting an IP address over wireless. Sometimes I can be successful simply by re-configuring the card and issuing dhcpcd a couple more time. I have noticed that on a failed dhcpcd request, my card configuration is sometimes out of whack, particularly the connection speed. If your card is usually set to 54M, you might try turning it down to 11M and see if that helps.