Hope you are doing well and sorry for the trouble. As described you are unable to share files and getting the error 'unable to connect to server'
Would you mind sharing the version of the Adobe Acrobat DC you are using? To check the version go to Help > About Acrobat and make sure you have the latest version installed. Go to Help > Check for updates and reboot the computer once.
Are you on MAc or Windows OS and what is its version? please check for any missing/pending updates for the computer OS and try updating it and check.
Also, please try to turn off the security software (For testing) installed on your machine that might be conflicting with Acrobat connection to Adobe server. Note: Please turn on the security after testing to avoid any security risks.
You may also try to create a new test user profile with full admin rights or enable the root account in Mac and try using the application there.