Creative Cloud applications need to periodically contact Adobe servers to verify that the plan is still active. If you are receiving the error message that the computer is Unable to reach Adobe servers, then see the following:
If an organization manages the computer you are using; please contact whoever manages the computer and network. Individual Creative Cloud memberships require access to the servers and ports listed in Adobe Creative Cloud Network Endpoints. If this is not possible, we recommend using a Creative Cloud for Teams or Enterprise membership. Both memberships provide additional flexibility on the need to contact Adobe servers.