This is a rather easy question.
If the sme server only has a natrouter in front of it, and this will nomally be the case, then it will not help at all to change the server port to 8080.
What can be done is to forward the external ip port 8080 to server ip and port 80. This will help, and your server will be available on internet on port 8080. Allmost any port that is open for an inbound connection can be used.
I have done these and simular things things houndreds of times and it works all the time.
external ip:8080----Forward via nat router-----to server ip:80