My Server Config:

   <?xml version="1.0" encoding="utf-8" ?>
    <configuration>
      <system.serviceModel>
        <services>
          <service name="[my-service-name]">
            <endpoint address="http://localhost:8005/MyService"
                  binding="webHttpBinding"
                  contract="[my-service-contract-name]"/>
          </service>
        </services>
        <bindings>
          <basicHttpBinding>
            <binding maxReceivedMessageSize="2147483647"
            maxBufferSize="2147483647"
            maxBufferPoolSize="2147483647">
              <readerQuotas maxDepth="32"
              maxArrayLength="2147483647"
              maxStringContentLength="2147483647"/>
            </binding>
          </basicHttpBinding>
        </bindings>
        <behaviors>
          <serviceBehaviors>
            <behavior>
              <serviceMetadata httpGetEnabled="true"/>
              <serviceDebug includeExceptionDetailInFaults="true"/>
              <dataContractSerializer maxItemsInObjectGraph="2147483647" />
            </behavior>
          </serviceBehaviors>
        </behaviors>
      </system.serviceModel>
      <startup>
          <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.6.1" />
      </startup>
    </configuration>


    My Service:

        [OperationContract]
        [WebInvoke(Method = "POST", UriTemplate = "MyService")]
        void MyService(String input)
        {
            Console.WriteLine("Request data = " + input.Length);
        }



Client Config:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <startup>
        <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.6.1" />
    </startup>
  <system.serviceModel>
    <bindings>
      <basicHttpBinding>
        <binding name="name-here" maxReceivedMessageSize="2147483647">
        </binding>
      </basicHttpBinding>
    </bindings>
    <behaviors>
      <serviceBehaviors>
        <behavior name="behavior-here">
          <dataContractSerializer maxItemsInObjectGraph="2147483647"/>
        </behavior>
      </serviceBehaviors>
    </behaviors>
  </system.serviceModel>

In your config, please add
"<dataContractSerializer maxItemsInObjectGraph="2147483647"/>"

Service Config:
<behaviors>
  <serviceBehaviors>
    <behavior>
      <serviceMetadata httpGetEnabled="true"/>
      <serviceDebug includeExceptionDetailInFaults="true"/>
      <dataContractSerializer maxItemsInObjectGraph="2147483647" />
    </behavior>
  </serviceBehaviors>
</behaviors>

Client Config:
<behaviors>
  <serviceBehaviors>
    <behavior name="MyServiceBehavior">
      <dataContractSerializer maxItemsInObjectGraph="2147483647"/>
    </behavior>
  </serviceBehaviors>
</behaviors>