Lease Pool Full on R-201 after firmware update and more than 255 IP addresses

We are having problems with people getting onto our network that is using the R-201 router. We recently upgraded the Firmware to 4.7.3 r-21. I tried shorting the lease time to 4 hours and I will see if that helps. Any other ideas? This wasn’t happening before the upgrade that we noticed. I also would like to know if this router can be set to have more IP addresses than 255.
Steve Schuh