Anytime you use any other port than 80 you're in "non-standard" port usage territory
There is a long standing issue with respect to DNN and the FriendlyURL provider
You need to do the following in your web.config:

Search for humanfriendly and change it to searchfriendly;
<friendlyUrl defaultProvider="DNNFriendlyUrl">
      <providers>
        <clear />
        <add name="DNNFriendlyUrl" type="DotNetNuke.Services.Url.FriendlyUrl.DNNFriendlyUrlProvider, DotNetNuke.HttpModules" includePageName="true" regexMatch="[^a-zA-Z0-9 _-]" urlFormat="searchfriendly" />
      </providers>


Enable port number:

<!-- set UsePortNumber to true to preserve the port number if you're using a port number other than 80 (the standard) -->
    <add key="UsePortNumber" value="true" />

Append the port # to the URLyou're using in your browser
You'll have the above changes in the web .config and a URL something like: www.mydomain.com:8080

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Ken Grierson
DotNetNuke Corporation
Test Lead

I finally figured out a work-around.  If you have a dynamic IP and your ISP is blocking port 80 and you want a domain like mydomain.com, then you need to setup a dynamic port forwarding domain name through no-ip.com by following these steps:

1. Setup a no-ip.com account and add your domain to no-ip.com (such as mydomain.com)
2. Go to your domain name provider (I used godaddy) and set the nameservers to no-ip.com nameservers(NS1.NO-IP.COM, NS2.NO-IP.COM) instead of godaddy's nameservers(NS43.DOMAINCONTROL.COM, NS44.DOMAINCONTROL.COM)
3. Setup mydomain.com to your current dynamic ip address (go to www.whatismyip.com and enter in that value)
4. Setup www.mydomain.com to web redirect to mydomain.com:8080 (or whatever port you are using)
5. If not already done, setup dnn and use portal alias -  localhost/dnn
6. Add mydomain.com:8080/dnn to portal alias table or add by going through host -> portals -> edit portal -> add portal alias
7. Download no-ip.com's Dynamic DNS Update Client (updates your ip on startup)
8. Voila, you now have a dynamic port forwarding website that displays mydomain.com:8080/dnn instead of 234.54.23.16:8080/dnn

If you are wondering why you have to set up www.mydomain.com to web redirect to mydomain.com instead of using the port forwarding option with no-ip.com, well here is the answer:
In order for DNN portal alias to work, the domain name (mydomain.com) ip address must point to your machine.  If instead you use port fowarding for www.mydomain.com and put in your current dynamic ip address and say, port 8080 and then ping www.mydomain.com you will not get your machines ip address ( it points to no-ip.com nameservers since it is a port forward)  So the only work-around I found is to do what is listed above.