I tried everything I could find / think of.
I'm running a webservice on IIS6 WSE2.0 on dotNet Framework 3.5 ASP 1.1
I changed the service and client web.config adding both:
<configSections>
<section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net"/>
<section name="microsoft.web.services2" type="Microsoft.Web.Services2.Configuration.WebServicesConfiguration, Microsoft.Web.Services2, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" />
</configSections>
<microsoft.web.services2>
<messaging>
<maxRequestLength>8000</maxRequestLength>
</messaging>
</microsoft.web.services2>
and then
<httpRuntime maxRequestLength="8000" executionTimeout="1200" />
in the system.web section.
But still anything over 4MB fails with: There was an exception running the extensions specified in the config file. ---> Maximum request length exceeded.