I don't know about that but we were having a problem because DU our internet provider was just providing us with 5 IP addresses and it was not enough. So dad got Apple Airport which gives out it's own IP addresses. The issue is about IP addresses and not about how many devices can connect to the router.
read what does a router means!! :D
simply saying it distribute the internet data of one IP (WAN) to the connected devices on local IP (LAN)
so if you had 5 IP before that means that your network provider has allowed 5 different WAN IPs to be assigned to your coonection
and right now you are using only one while distributing the data of that IP on further LAN IPs.