The following error (Unable to login!The remote server returned an error: (401) Unauthorized.) from DPD is caused when they are not accepting the credentials we are providing them. There are three common causes for this:
Incorrect Username and/or Password - Please make sure the credentials are correct and that there are no hidden spaces
Incorrect Account Type - Please ensure that the correct account type has been set for the credentials you are using IE if you have a DPD local account, you need to set the Type to INTERLINK
If the DPD account has recently been setup and the above is correct, then the account owner will need to contact DPD to enable API access as newly created DPD accounts do not have this enabled by default.