Ok I got a reply:
Thank you for choosing Amped Wireless,
The R20000G can handle 16 wireless clients per radio. The R20000G has two radios, so it can handle up to 32 wireless clients. if you have any further questions, please feel free to email us or contact us at 888-573-8820.
So as I suspected just because it has 100 IPs available it can only handle a fraction of that and any one time. Most home routers are like this