I'm using Magento with WebGility & QuickBooks and QuickBooks POS is connected successfully but the WebGility status page continues to redirect to another domain rather than stay on the status page. WebGility error states: The input is not a valid Base-64 string as it contains a non-base 64 character, more than two padding characters, or an illegal character among the padding characters.
WebGility says it's a developer problem & will not assist with fixing the issue.
Which module are you using for the integration?
Have you tried adding https:// at the start of the URL instead of http://