WCF SOAP 404 error

Question

I've developed a WCF SOAP Web Service and for testing purposes i use SOAP UI but i have the following problem:

1) I test the Web service using the ip adress like this:

http://XXX.XXX.XXX.XXX:81/SIDIGE.Web.Service.CanDoc.svc?wsdl

and everything works FINE, I can use the web service without issues

2) Now if I test the Web service like this (using the hostname):

http://hp_webserver:81/SIDIGE.Web.Service.CanDoc.svc?wsdl

I get a 404 error when i POST info to the server (if I use the browser and type the address it works, no 404 error)

I've read all questions about this and nothing seems to work....any ideas?

My web.config is:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
    <connectionStrings>
        <add name="servidorRemoto" connectionString="Data Source=XXX\XXX; Initial Catalog=XXX" providerName="System.Data.SqlClient" />
    </connectionStrings>
    <appSettings>
        <add key="aspnet:UseTaskFriendlySynchronizationContext" value="true" />
    </appSettings>
    <system.web>
        <compilation debug="true" />
    </system.web>
    <!-- When deploying the service library project, the content of the config file must be added to the host's 
  app.config file. System.Configuration does not support config files for libraries. -->
    <system.serviceModel>
        <services>
            <service name="SIDIGE.Web.Service.CanDoc" behaviorConfiguration="ServiceBehavior">
                <endpoint address="CanDoc" binding="basicHttpBinding" contract="SIDIGE.Web.IService.ICanDoc" bindingNamespace="http://sidige.com/candoc" />
                <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" />
                <host>
                    <baseAddresses>
                        <add baseAddress="http://XXX.XXX.XXX.XXX:81" />
                    </baseAddresses>
                </host>
            </service>
        </services>
        <behaviors>
            <serviceBehaviors>
                <behavior name="ServiceBehavior">
                    <serviceMetadata httpGetEnabled="True" httpsGetEnabled="True" />
                    <serviceDebug includeExceptionDetailInFaults="True" />
                    <useRequestHeadersForMetadataAddress>
                        <defaultPorts>
                            <!-- Use your own port numbers -->
                            <add scheme="http" port="81" />
                        </defaultPorts>
                    </useRequestHeadersForMetadataAddress>
                </behavior>
            </serviceBehaviors>
        </behaviors>
    </system.serviceModel>
    <system.webServer>
        <directoryBrowse enabled="false" />
    </system.webServer>
</configuration>

Answer 1

The problem wasn't on my part or the configuration. It was the testing client (SOAP UI). It seems it has some issues with proxy networks.