@wes Anything your ISP support team state takes precendence, but if you're comfortable changing the config of your modem/router, my first step would be lowering the security (temporarily!!!).
Set it to nothing, reboot modem/router, wait a few minutes, and see if your "new" devices can now see and connect to the network.
If they can, raise security to WEP on your WiFi (laughable "security" but for trouble shooting...). Check a still "new" device, and see if WEP password accepted. If it is, try upping WPA1 security (reboot, wait etc) and see if a still "new" (not connected to wifi yet) device can see and connect. If this somehow works, raise the security back to WPA2 on WiFi, recheck.
Oh, one final thing, only just clicked... check you don't have ANY type of MAC filtering going on there in the modem/router. Check with your manual/support docs, but if older devices were known MAC addresses, I can see how some devices now could be blocked out purely because their MAC isn't whitelisted.