Comment 73 for bug 496093

I found a workaround. Using WPA on the router but probably WPA2 would be fine. Definitely NOT mixed.
It seems important that the client does not think it is reusing a previously allocated IP, which is consistent with the reported intermittent behaviour and generally OK first time connection.
I configured the router to allocate a specific IP for the client's MAC and also cleared the DHCP leasing table on the router. I set leases to expire in just 5 minutes. Having done this, the router need not be touched again. Thereafter, every time I try for a new connection from my Lucid client, I first disable networking and then re-enable it. The first time, use DHCP and get the specified IP. Then, break the connection and Edit connections. Set IPv4 to fixed IP, the same as specified on the router for that MAC.
This is all pretty convoluted, but it's the only way I could find that works consistently. Your results may vary. Good luck. I wasted a day on this.