I just added a block of 5 additional fixed IP addresses and I can't seem to make it work. To test it I added one of the new WAN IP addresses on the 1/1 NAT page on the gatewway and mapped it to a fixed local address that has been reserved from DHCP. DHCP is being provided by a server on the LAN, not the gateway. The machine using the local fixed address seems to lose DNS and I cannot access it or connect to it from the WAN. Is there something elsee I need to do? This was pretty straightforward withour old ADSL router but I can't seem to make it work on the business cable gateway.
i am not sure why the 1-to-1 NAT is not passing through traffic; the fact that DHCP is not being handled by the gateway might be a part of it. can you maybe post screenshots of your Comcast gateway config, blanking out any sensitive IPs/info? Have you tried running a packet monitor on your internal host, then pinging your NATted public address from somewhere else on the internet? just to see if any packets at all are reaching your hosts? as well, check out the "Connected Devices" link on your Comcast gateway & make sure your hosts show up there.
i might ask though, is there any reason why you don't just configure your hosts with your public assigned addresses, rather than worrying NATting the public addresses to the private ones? (e.g., configure your host with 220.127.116.11, instead of 10.1.10.x?)