Desktop Central MSP Public FQDN no NAT Local DNS Pointer

Do I have to use a NAT on my firewall for Desktop Central MSP. I have ServiceDesk Plus MSP setup on the same server as my Desktop Central MSP " Just Setup Testing". I have a Public FQDM for both and both are setup on the public DNS. SDP.mydomain.net DTC.mydomain.net.

I have setup my local DNS to point SDP & DTC to local server address " 192.#.#.#". From a public computer, I can access SDP using Http://SDP.mydomain.net:8070 and everything works great..

But from the same public computer if I use Http://DTC.mydomain.net:8040 I can't access Desktop Central MSP it times out. I know the request is getting to the correct local server because if I use Http://DNS or DTC.mydomain.net I get the IIS Page.I have also set the local server host file with the 192.#.#.# SDP.mydomain.net and DTC.mydomain.net.

So why does SDP work and DTC not work?

Does DTC have to have a NAT or did I miss something?

Sorry, the rule in the firewall has all the port for both setup just not nated.

Thanks