Ok before you replied I found this and followed the instructions and installed the certificate and verfied that Extensible_Service_Setup is on. Still same error Unable to connect to remote server.
It sounds like you don't have the appropriate Root Certificate Authority file on the MFP. To resolve your issue you can do one of two things:
1. Disable the Verify Server Certificates from MFP's Centreware home page
2. Load the appropriate certificates.
Is there any way we could talk live? I am getting a certificate error when I login to dropbox at the control panel. Error message is certificate error..the ssl certificate for the website could not be verified. https://xas-mid-prod.services.xerox.com/XeroxScan.ashx is listed on the control panel and on the printed error page. This might be a clue.
That's the same machine and software I use. The machine is obviously connecting to the xas-mid-prod server from the browser since you're browsing your dropbox account. The issue seems to be the scanner system can't connect to it, which is why I thought the proxy would be the likely cause.
It's just your 78xx that has the issue though since I can scan from my MFD. I'm pretty sure it's settings network related on the device based on how you described the problem but we can rule out a network issue if you have can test on another MFD. Also see if you can change your machine's DNS server to 126.96.36.199 (that's google's DNS servers)
Also try restarting the machine see if the settings correct themselves on a reboot.