Based upon your response, (and especially once you started talking about changing a port within code server, you're attempting to do it wrong.
With port mapping (bridge networking mode), it's completely irrelevant if multiple containers all use the same internal ports (in your case 8443) or not. All you have to do is change the host port referenced in the template. Everything else webUI etc will follow the applicable changes...
You pretty much never need to change the internal container port.