NO the modem itself does not have a maximum user limit that you have reached... based on what you have listed. The router firmware within this model is capable of handling DHCP requests for up to 254 devices total.
This is your modem, correct?
This does not automatically mean that it should be working the way you expect.
The problem here is in the settings. First... have you contacted your ISP (since they provided you with the modem and the contract you are currently using to connect) and asked them how many devices you are allowed to connect to the modem? You might be surprised with their answer. You might be surprised to find that they actually have a contractual limit on the number of devices... or at the very least that there is a default setting that only passes out 10 internal IP addresses.
Now... if you don't want to contact your ISP (which is what I would have done before posting a question here, but that's just me), you can go out, purchase a third party wireless router, and follow the instructions here to set up your modem as a transparent bridge. Why would you want to do such a thing? Well, for one, you are only monkeying around with a minimum number of settings. For another, you shouldn't have to contact your ISP.
It is possible to expand the DHCP range for your Qwest modem. Doing so might just violate your TOS with your provider.