dhcp configuration for wireless

I have a marginal snr situation for wireless.
I have a router with only 3 or 4 leases to give out.

I _suspect_ that the following is happening:
After three or four drop-outs, the router says there's no more new leases to be had. It doesn't know all the leases still running are mine already. I can get a new lease if I reboot, but this seems so crude and unnecessary.

I note that Mepis has a file /etc/dhcp3/dhclient.conf, but I know there is something similar on the router. Both Mepis and the router have client definitions and lease parameters.
Where do I start to improve on this situation?

yeti, using 6.5 rc 2, all the latest.